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Phosphorus (P) limitation in acidic soils is well known and P-use and -recovery efficiency (PUE and PRE) is quite low. Rhizosphere-based P management has been considered as a means of enhancing PUE in acidic rice soils, but no clear dynamic study on this context. Rice was grown in pots using different P-sources [rock-phosphate (RP), single-super-phosphate (SSP), compost, P solubilizing bacteria (PSB), PSB + RP, PSB + compost, and compost + PSB + RP] in acidic Inceptisols (pH 4.31). Additionally, a micro-plot field experiment validated the results, using control, SSP, RP, PSB, and PSB + RP. Available-P (AvlP) and pH were analyzed every 10-days, while acid-phosphomonoesterases activity (PHA) and P-uptake in every 30-days until harvest. AvlP was peaked at 20 days after transplanting (DAT) and decreased until harvest. Compost + PSB + RP maintained significantly higher AvlP, soil pH and PHA, while root volume was highest in SSP throughout the growing period, and Soil pH showed an asymptotic trend. The P-content and uptake in biomass showed the highest peak at 60DAT and gradually declined until harvest. The effects of SSP and compost + PSB + RP on grain yield, chlorophyll concentration index (CCI), grain P content and uptake were comparable, but PUE and PRE were higher in compost + PSB + RP. Similar result was also observed in micro-plot field experiment, wherein grain yield and P uptake were comparable in SSP broadcast and PSB + RP. The study clearly shows that the combined application of PSB with RP, compost, or both in a 50% reduced amount can maintain higher AvlP in rice in acidic soil compared to full dose SSP while achieving a comparable yield. [ABSTRACT FROM AUTHOR]

Blackberry is grown in a wide range of soil pH, and it is known that the adequacy of soil pH is essential for plants to express their maximum nutritional efficiencies and, consequently, reach their maximum productive potential. Thus, the objective was to evaluate the nutritional accumulations and efficiencies for maximum fruit production. The experiment under greenhouse conditions was carried out in a randomized block design followed by a 4 × 2 × 4 factorial scheme with three repetitions. The evaluated factors were four blackberry cultivars (Tupy, Brazos, Guarani, and Xavante) grown in two types of acidic soils (Typical Hapludox [TH] and Rhodic Hapludox [RH]) to which four rates of dolomitic limestone (0, 1.5, 3.0, and 6.0 Mg ha−1) were applied. Fruit production and nutrient accumulation in the fruits, leaves, stems, and roots of the plants were evaluated, as well as the nutritional efficiency of each cultivar. The blackberry cultivar Tupy has been the most productive, independent of the liming rate. Blackberry cultivars have shown differences in nutrient accumulation and efficiencies for maximum fruit production, and they also have distinct nutritional requirements. [ABSTRACT FROM AUTHOR]

The productivity of soybean in Assosa Zone particularly in Assosa and Bambassi districts is very low due to poor soil fertility management practices which resulted in severe soil acidity and low N-fixing inoculant in the soil. Hence, this experiment was conducted during the main cropping season of 2019 and 2020 in Assosa and Bambassi districts to evaluate the effect of biofertilizers, lime, and inorganic NPSB fertilizers on nodulation, growth, and yield of soybean (Glycine max L. Merrill). Factorial combinations of four biofertilizer inoculants [without biofertilizer (B1), SB12 biofertilizer at the recommended rate of 500 g ha −1 (B2), MAR1495 biofertilizer at the recommended rate of 500 g ha−1 (B3) and SB12 plus MAR1495 biofertilizers at their recommended rates (B4); two lime rates named without lime (L1) and lime at 5 ton/ha (L2); two inorganic NPSB fertilizers NPSB at 9.5-23-3.5-0.05 (F1) and NPSB at 19-46-7-0.1 (F2) at their recommended rates for soybean] were laid out in a randomized complete block design (RCBD) with three replications. Effective nodules, leaf area index, and grain yield were collected and analyzed using SAS 9.1.3 version software. Results of the experiment showed that effective nodules per plant, leaf area index, and grain yield were affected by biofertilizers, lime, inorganic fertilizers, and their interactions significantly (p < 0.01) at both locations and years. Finally, the interaction of SB12 + MAR1495, lime at 5 t/ha and NPSB at 19-46-7-0.1, and the interaction of SB12, lime at 5 t/ha and NPSB at 19-46-7-0.1 gave the maximum grain yield at Assosa and Bambassi, respectively. [ABSTRACT FROM AUTHOR]

Winter canola (Brassica napus L.) is a potential alternative to winter wheat in Oklahoma rotation systems as a means to overcome the negative impacts of continuous wheat systems. However, its performance may suffer in the acid soils that are common to intensive agriculture systems in the southern Great Plains region. The objective of this study was to quantify the impact of soil pH and Al3+ concentration on winter canola production. Two field trials were conducted in 2016 and 2017 across four different locations in central Oklahoma to evaluate the performance of four canola cultivars in soils with a range of pH from 4.0 to 8.0. Yield, soil pH, and Al3+ concentrations were measured from each plot to study the relationships between these variables. At all but one location, soil pH and Al3+ concentrations were inversely related and when data across these locations were combined, Al3+ concentrations decreased as pH increased to a critical value of 4.8 (r² = 0.83). In general, it was found that yield decreased linearly as pH decreased below 5.8 (r² = 0.75) and increased linearly as Al3+ concentrations decreased below 87 mg kg-1 (r² = 0.73). Above these thresholds, yield was unrelated to pH or Al3+ concentrations. It was also observed that at one location with very low naturally occurring Al3+, high canola yields were achievable even in low soil pH. Therefore, Al3+ concentrations may be a better indicator of the effects of acidic soils on winter canola yields than pH values alone. [ABSTRACT FROM AUTHOR]

Cowpea has great capacity of biological fixation of nitrogen (BFN) in association with Rhizobium. However, it is not known whether the interaction of liming, mineral N fertilization, and Rhizobium-inoculated seeds can modify the efficiency of BFN, and still, result in gains in biomass production and yield in cowpea. This study evaluated the use of liming associated to Rhizobium-inoculated seeds and supplemental mineral N fertilization on the nodulation improvement, biomass production, and on the increase of cowpea grain production. Two experiments were conducted under field conditions in two consecutive years, using the same treatments and experimental design. The treatments were conditioned in a split-plot scheme in randomized blocks with four replications in a 2 × 6 factorial, the first factor being two cowpea cultivars (BRS Tapaihum and BRS Marataoã) and the second factor was considered six conditions of corrective practice and N supply [no N supply and no liming (T1), liming + rhizobium (T2), rhizobium (T3), liming + mineral N (T4), liming (T5), and liming + mineral N + rhizobium (T6)]. Nitrogen concentration and accumulation in the leaves increased with liming and N supply (T2, T4, and T6) and increased dry matter (DM) accumulation in the stem, leaves, shoots, and total DM. The absence of liming limited root length growth, decreased root DM, and the number and DM of nodules thus limiting grain production. Additionally, N fertilization supplemented with Rhizobium-inoculated seeds did not increase grain production. However, the use of liming and the inoculation of seeds with Rhizobium increased plant performance and improved grain yield of both cowpea cultivars. [ABSTRACT FROM AUTHOR]

High soil pH constrains the availability of many plant nutrients including phosphorus (P). Sulfur (S) application to soil is a commonly used method to reduce the soil pH in the plant root zone, increase the availability of nutrients and thus obtain a higher yield. However, the particle size of the S is the most important factor in decreasing the soil pH. This study aimed to investigate the effect of different doses of micronized S application (0, 125, 250, and 375 kg ha−1) on the chemical properties of calcareous soil and the yield and nutrient contents of two wheat cultivars (Burgos and Zhivago). The results indicated that soil pH and CaCO3 content of soil decreased with increasing doses of S application. Soil organic carbon content slightly increased with all S applications in Burgos wheat variety. The highest increase was recorded in the 375 kg ha−1 S application, but no significant difference was determined in the Zhivago variety. The available Cu content in soil varied between 3.43 and 3.55 mg kg−1, Fe content was between 13.86 and 14.93 mg kg−1, Mn content was between 22.73 and 25.65 mg kg−1, and Zn content was between 0.53 and 0.62 mg kg−1. The results revealed that soil pH and CaCO3 content decreased with liquid micronized S applications, however, the effect of S applications on exchangeable cations and heavy metal content was not significant. [ABSTRACT FROM AUTHOR]

North-Eastern India is blessed with a vast diversity of rice genotypes with varying yielding abilities. However, the predominant strong soil acidity induced nutrient stresses from the toxicity of aluminum (Al3+) ions often causes sub-optimal rice productivity. The lack of suitable nutrient media for the screening of aluminum (Al) toxicity tolerance of rice genotypes is one of the limiting factors in Al tolerant varieties' development. Modified Magnavaca's solution has been the most recommended nutrient solution for this purpose where ammonium nitrate is the primary nitrogen source. However, strict regulations related to the handling and storage of ammonium nitrate in India limit the preparation of Modified Magnavaca's solution for laboratory use. Here, a modified ammonium nitrate-free formulation based upon the Magnavaca's solution has been proposed. The modified formulation was found to have 160.9 µM of active Al3+ concentration when 550 µM of aluminum chloride hexahydrate (AlCl3.6H2O) was added at pH 4.1 to the solution. Through a plant growth screening experiment using ten diverse rice genotypes a significant difference in the response of various genotypes to differential Al toxicity levels on root growth performance indicators was observed. Based on the response, we could able to categorize the genotypes into tolerant and sensitive in relative terms. Thus, the present experiment provided an important nutrient formulation suitable for screening rice genotypes under Al toxicity conditions. Moreover, the selected tolerant and sensitive genotypes can further pave the way for studying the molecular mechanism of Al toxicity response in rice and their use in the breeding program. [ABSTRACT FROM AUTHOR]

Soil acidity and very low nutrient status are major production-limiting factors for maize production in most parts of the savanna agroecological zones (AEZ) of northern Ghana. Therefore, effective nutrient management is critical to increase productivity. During a two-year study across six locations in the Guinea Savanna AEZ in northern Ghana, we evaluated the interactive effects of liming and balanced fertilization on maize productivity in acid soils. Six fertilization strategies – (i) balanced (containing all essential limiting nutrients), (ii) balanced with sulfur omitted (minus-S), (iii) balanced with zinc omitted (minus-Zn), (iv) balanced with boron omitted (minus-B), (v) NPK-only, and (vi) control (no nutrients supplied) – were evaluated, each with or without liming. Applying only lime without fertilizer application increased maize yield from an average of ∼0.55 t ha − 1 to ∼0.92 t ha − 1. For NPK-only fertilization, liming led to an increase in yield from an average of ∼1.68 t ha − 1 to ∼2.84 t ha − 1. For balanced fertilization, lime application resulted in an additional maize grain yield of ∼53% compared to treatment without lime application. With liming, the minus-Zn treatment resulted in a significant yield decrease of an average of ∼30% compared to balanced fertilization, suggesting that combined application of lime and Zn should be advocated to better sustain crop productivity in this region. We conclude that, to improve maize productivity in acid soils in order to ensure increased profitability and improved household income, fertilizer recommendations that promote balanced fertilization must include liming as part of the nutrient application package. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of liming on soil fertility, growth, nutrition and production of red pitaya (Hylocereus monacanthus) plants cultivated in pot. The experiment was conducted in blocks, with five doses of limestone (0.0; 0.6; 1.2; 1.8; and 2.5 t ha−1) and four replicates. Corrective doses were established to achieve base saturation of 20 to 70%. Liming increased soil pH (4.5 to 6.7), Ca concentration (5.36 to 20.11 mmolc dm−3), Mg concentration (4.36 to 16.53 mmolc dm−3) and base saturation (23.69 to 72.61%) and reduced potential acidity (37.39 to 15.41 mmolc dm−3). Liming reduces nitrogen concentration and increased phosphorus, calcium and sulfur concentrations in the cladodes. There was an increase in phosphorus concentration and decrease in boron and iron concentrations in fruit peel according to the increase in limestone doses; in the pulp, there was an increase in boron concentration and decrease in iron and zinc concentrations, from the lowest to the highest dose of limestone. Based on the principal component analysis, the limestone dose of 1.8 t ha−1 increased base saturation to 59%, providing favorable chemical conditions for the growth and productivity of red pitaya. [ABSTRACT FROM AUTHOR]

Compost tea comes from a wide range of sources and can provide nutrients for crops and improve soil quality. In order to explore the effects of fertilization frequencies of compost tea on the spatial distribution of nutrients and the uptake by cotton, a trial comprised no fertilization treatment (CK) and three fertilizer treatments, that is, the application of a fixed amount of fertilizer at four (F3), two (F5), or one (F9) irrigation cycle, and each irrigation cycle was 10 days. The total amount of nutrients (N, P2O5, K2O) in fertilization treatment were all 18 g, and their amount of fertilization each time was 1/3, 1/5 and 1/9 of the total fertilizer, respectively. The results showed that in 0–10 cm soil layers, high-frequency fertilization (F9) reduced the soil pH by 5.6% compared with F3, the soil nutrient content of F3 treatment at seedling stage was significantly higher than that of the other two treatments by 71.9%–272.3%, however, the 20–40 cm soil layer was hardly affected by fertilization; The nutrient accumulation of cotton in F3 treatment was 17.1%–32.4% higher than that in the other two treatments, and the highest dry matter and recovery efficiency were also obtained under the F3 treatment. In conclusion, increasing the proportion of fertilization in seedling stage (F3) can increase the uptake and utilization of nutrients by cotton; While high-frequency fertilization (F9) can reduce the pH of calcareous soil. This study provides a basis for fertilizer optimization and soil quality improvement of composted tea. [ABSTRACT FROM AUTHOR]

A field experiment was conducted at Zonal Agricultural Research Station, Mandya to evaluate the effect of biochar, lime and fertilizer on soil acidity and microbiological properties in an acidic soil. The experiment was laid out in randomized complete block design with seven treatments and three replications. The results revealed that application of fertilizer based on the soil test value (STV) either in combination with biochar or lime influenced soil microbial biomass carbon (SMBC), soil microbial biomass nitrogen (SMBN), dehydrogenase, urease and phosphatase activities significantly. Similarly, application of STV-based fertilizer along with biochar+FYM (Farm Yard Manure) + ZnSO4 significantly decreased exchangeable aluminum, exchangeable acidity and total acidity as compared with recommended dose of fertilizer (RDF) + FYM+ ZnSO4 treatment. The grain yield of rice was increased by 37.90% in STV + biochar + FYM + ZnSO4 and by 22.87% in STV + lime +FYM + ZnSO4 plots than RDF + FYM + ZnSO4 plot. Seed and haulm yield of cowpea increased by 33.57% and 18.53% in STV + biochar + FYM + ZnSO4 treatments as compared with RDF + FYM + ZnSO4 treatment. Exchangeable aluminum and exchangeable acidity were found to be negatively correlated with yield of rice (r = -0.179) and cowpea (r = -0.266). However, yield of rice and cowpea showed the significantly and positively correlated with microbiological properties. The exchangeable Al and exchangeable acidity were found to be negatively correlated with SMBC, SMBN, dehydrogenase activity, urease activity and phosphatase activity. [ABSTRACT FROM AUTHOR]

Sub-optimal productivity in cashew is common in tropical India due to inadequate attention on plant nutrient management. Identifying the nutrient constraints, its diagnosis and management are important for maximizing production in a sustainable manner. We established nutrient diagnostic norms for cashew that shall be useful for quick diagnosis of the nutrient requirement of cashew for devising rapid nutrient management schedule to improve the productivity. The optimal leaf nutrient status in cashew for nitrogen, phosphorus, potassium, calcium, magnesium and sulfur ranged from 2.23 to 2.82, 0.13 to 0.18, 0.91 to 1.47, 0.92 to 1.39, 0.46 to 0.70 and 0.75 to 1.14% respectively. The optimal leaf status for micronutrients such as iron, manganese, zinc, copper, boron and molybdenum ranged as 285 to 398, 200 to 409, 54 to 74, 47 to 60, 22 to 46 and 3.0 to 4.4 mg kg−1. The regional survey on soil and leaf nutrient status of cashew in prominent cashew growing areas along coastal India revealed the nutrient constraints causing lower productivity levels. The cashew growing soils in India were predominantly deficient in nitrogen, potassium, calcium, magnesium, zinc and copper. The study indicated the ill effects of neglect of fertilizer and manure application in cashew on soil organic carbon, nitrogen and potassium, which adversely affected the nutrient uptake by cashew as evident from the leaf nutrient status. The study also highlighted the need to pay attention to soil ameliorants to correct soil acidity to make available calcium, magnesium and micronutrients such as zinc, copper and manganese. [ABSTRACT FROM AUTHOR]

Mulberry (Morus indica L.) is a foliage crop cultivated extensively in the North-Eastern India under rainfed condition for rearing silkworm (Bombyx mori L.). An attempt was made through field experimentation to develop a soil-cum-nutrient management package for mulberry cultivation in acid soil under rainfed condition. Effects of different treatment combinations comprising of NPK, farmyard manure (FYM), lime and boron (B) on important soil properties, yield and quality of mulberry (Morus indica L. var. S1635) leaf were assessed to identify the best soil-cum-nutrient management package. Results indicated that fertilizer dosage based on ready-reckoner soil test value was not effective for the production of high-quality leaf with specific targeted yield of the crop (4.5 t/ha/crop-cutting). Integrated soil application of NPK @ 150:50:50 kg ha−1, FYM@10 t ha−1, lime as per requirement (3t ha−1 in present case) and foliar application of boric acid solution (0.1% w/v) was the most effective soil-cum-nutrient management package for the production of higher leaf yield which is comparable with the targeted yield. As far as leaf quality is concerned, increased moisture content, total N, P, K and B content of leaf are also attributed to the package. The package resulted in increased pH, organic carbon, dehydrogenase activity, available N, P, K and decreased exchangeable aluminum, exchangeable acidity and total potential acidity of soil. The study indicates the usefulness of soil-cum-nutrient management package for improved soil health of acid soils as well as achieving high yield and quality of mulberry leaf in such acid soils of the North-Eastern India and elsewhere. [ABSTRACT FROM AUTHOR]

Phosphate solubilizing bacteria (PSB) is renowned for its excellent potential of converting unavailable forms of phosphorus (P) to a simpler available form in the soil. This P availability not only improves plant growth and differentiation but also plays a pivotal role in balancing the soil mineral content. This study focuses on the effect of PSB alone or in combination with di-ammonium phosphate (DAP) on the growth and development of sunflower. The hybrid sunflower seeds inoculated with PSB were placed in the pots containing sterile soil. Five PSB strains, three doses of DAP, and un-inoculated seeds as the control for each dose of DAP were used. Various parameters of plant growth and soil properties were measured after 60 days of sowing. The results indicated that PSB inoculations enhanced the P mobilization efficiently in the sunflower plant and increased its growth. It also improved the availability of P in soil with a decline in soil pH. However, when PSB was used with a combination of DAP, much vaster results were noticed. Improvements in all plant growth parameters without the inoculation were higher at 30 mg kg−1 DAP, which is about at 23 mg kg−1 DAP when it is used in combination with PSB. Maximum SPADE chlorophyll contents, plant height, root length, fresh weight, dry weight, shoot P content, and available P in soil were assessed in AM-4 (Pseudomonas sp.) at all doses of DAP. However, the plants that were treated with 30 mg kg−1 DAP showed superior results in terms of growth. The results from the study conclude that PSB can be used alone or in combination with DAP to enhance the growth of sunflower and to solubilize the fixed soil P. [ABSTRACT FROM AUTHOR]

Dunite [(MgFe)2SiO4] is an igneous rock that remineralizes and corrects soil acidity as well as providing magnesium (Mg2+) and silicon (Si4+) to several crops of agricultural interest. However, few studies have verified its solubility in tropical soils, which is important for its use in different tropical conditions. In a greenhouse incubation experiment, this study verified the solubilization kinetics of dunite in clayey, medium texture, and sandy soils. The soil samples were dried and sieved (50 mesh), placed in plastic cups (300 g), and incubated for six months (at 60%–80% of the moisture retention capacity). Samples for pH (CaCl2 extractor), Mg2+ (resin extractor), and Si4+ (CaCl2 extractor) analysis were taken at 10, 20, 30, 40, 50, 60, 70, 85, 100, 115, 130, 150, and 180 days after incubation. The application of dunite led to an increase in Mg2+ and Si4+ contents and an acidity correction in the three studied soils. Its controlled release presents method for increasing the efficiency of magnesium fertilization. It allows for fewer losses due to Mg2+ leaching, as the dissolution kinetics are slower than soluble sources and have a residual effect for subsequent crops. [ABSTRACT FROM AUTHOR]

Thermomagnesium (TM) or magnesium silicate (MgSiO3), is originally from the nickel (Ni) industry, and is a by-product that provides magnesium (Mg) and silicon (Si) to plants and corrects soil acidity. Some studies verify its solubility in tropical soils. This study evaluated the application of TM in two particle sizes (20 and 100 mesh), in sandy and medium-texture soils (Typical Oxisol), and a clayey texture soil (Typical Ultisol), in a six-month incubation experiment in a greenhouse. The soil samples were dried and sieved, placed in plastic pots, and incubated from 60 to 80% of the moisture retention capacity. Samples for pH analysis (CaCl2 extraction), Mg2+ (resin extraction) and Si4+ (CaCl2 extraction) were taken at 10, 20, 30, 40, 50, 60, 70, 85, 100, 115, 130, 150, and 180 days of TM incubation in the soils. The application of 100 mesh TM was superior owing to its greater contact surface, which increased the soil content of Mg and Si, and corrected the acidity in the three soils that were studied. The controlled release of TM (100 mesh) increased Mg fertilization efficiency, since less Mg2+ is lost by leaching, owing to the slower dissolution kinetics than soluble sources. The TM adjusts to the demand of the plants and has a residual effect for subsequent crop seasons. [ABSTRACT FROM AUTHOR]

Phosphate fixation is a main factor limiting phosphate availability and reducing crop production in acidic soils. Although biochar addition has been suggested as a means of ameliorating acidic soils, questions remain about the impacts of biochar on phosphate fixation and availability in these soils. To address these questions, a biochar produced from sugarcane bagasse was added at four different levels (0, 1, 3, and 6% w/w) to an acidic soil. After 30 days of incubation, comparisons were made between the chemical properties of the biochar-amended soils and those of the original one. Sorption isotherm experiments were also conducted to estimate soil phosphate sorption capacity and affinity parameters under biochar amendment. Results showed that biochar application improved such soil chemical properties as pH and cation exchange capacity as well as exchangeable calcium, magnesium, sodium, and potassium cations. Biochar was also observed to increase phosphate sorption capacity of the soil but reduce its phosphate sorption strength, indicating that biochar-amended soils were potentially able to fix lower amounts of phosphate than the original acidic soil was. Moreover, soil phosphate buffering capacity indices decreased as a result of biochar incorporation, indicating the easier release of phosphate from the solid to the solution phase in biochar-amended soils. Biochar addition was also observed to reduce effectively (up to 62%) the standard phosphorus requirement of the soil. In conclusion, biochar amendment was found to induce positive changes in phosphate sorption properties of acidic soils, thereby providing conditions more favorable to plant growth through sufficient phosphate availability. [ABSTRACT FROM AUTHOR]

Two lysimeter experiments were conducted to evaluate the impacts of biosolids and drinking water treatment residual nanoparticles (nWTRs) on phosphorus and aluminum phytoavailability and yield of corn plants. Two consecutive experiments were conducted with different application rates of biosolids (0% and 3%) and nWTRs (0%, 0.1%, 0.2%, and 0.3%). The results revealed that the total biomass production (grain plus stover) increased significantly (p <.05) as a result of nWTRs application at 0.1% rate. Application of nWTRs to biosolids-treated soil slightly decreased yield at 0.2% and 0.3% application rates. The best combination ratio between nWTRs and biosolids at which high corn yield is 0.1% nWTRs to 3% biosolids. Application of 3% biosolids significantly increased bioavailable P in the studied soil, but application of 0.3% nWTRs significantly decreased the bioavailable P concentrations in soil in the two seasons of cultivation. Application of nWTRs at 0.1% and 0.2% rates decreased soil pH in the soil treated with 3% biosolids in first and second seasons of cultivation in comparison with control treatment. The application of nWTRs greatly and significantly (p <.05) increased the water-holding capacity of studied soil treated with and without biosolids. [ABSTRACT FROM AUTHOR]

Soybean production in the Cerrado area is limited by the acidity and excess of aluminum in the soil. Thus, the use of agricultural lime and gypsum is necessary to decrease these factors and favor soybean growth. This study aimed to evaluate the effect of the application of lime and gypsum doses on soybean yield and nutrition, in a no-tillage system (NTS). The experiment consisted of a completely randomized blocks design, with four replications, and tested lime doses (0, 2, 4, 8, and 10 t ha−1) combined with the gypsum doses (0, 1, 2, and 4 t ha−1), applied to a Xanthic Haplic Ferrasol, in a Cerrado area intended to the implantation of a soybean crop under NTS. The traits leaf nutrition, hundred-grain weight, and the grain yield were evaluated in the 2015/2016 and 2016/2017 seasons. The application of lime combined with gypsum significantly changed the calcium content in the leaf, hundred-grain weight, and yield in the 2015/2016 season, and hundred-grain weight in the 2016/2017 season. Lime doses increased soybean nutrition for Ca, Mg, and yield in two seasons; however, are decreased N and K. N, P and Mg (season 2016/2017) are increased by Gypsum doses and decreased K and Mg (season 2015/2016). [ABSTRACT FROM AUTHOR]

Blending polymer-sulfur coated urea (PSCU) and conventional urea (U) for maize (Zea mays L.) fertilization can supply nitrogen (N) during the crop cycle with a single application. Proper placement of PSCU + U (0.15 m below and 0.1 m to the side of seed row) in band application at sowing is necessary to reduce salt stress that can decrease dry weight (DU) and N uptake (NU) of maize plant compromising maize yield. It is not clear the proper N rate in the proper placement for band application of PSCU + U at maize sowing to avoid salt stress. In the current literature, reduction of N rates are being recommended using PSCU + U without consider the probably salt stress provided by high rates of PSCU + U. DW and NU in maize plant as well as soil pH and electrical conductivity (EC) were evaluated in a greenhouse pot trial. N treatments were equivalent to 0, 90, 180, 360 and 540 kg N ha−1 applied incorporated in band in two contrasting soils (Rhodic Eutrustox and Typic Haplustox) using 70%PSCU + 30%U. At V10 (vegetative leaf stage 10), DW and NU of maize aerial part had quadratic behavior in response to increase N rates in the Typic Haplustox soil. In the Rhodic Eutrustox was not observed known behavior for DW and NU in response to increase N rates. Soil pH and EC was higher in the fertilizer row than sowing row. A N rate above of 180 kg N ha−1 using 70%PSCU + 30%U incorporated in bands can reduce DW and NU in early maize plant growth associated with salt concentration of N fertilizer in a Typic Haplustox soil, which could compromise maize yield. [ABSTRACT FROM AUTHOR]

Misuse of fertilizer on Codonopsis. lanceolata is extensive due to scarce information concerning its nutrient absorption and requirement. The objective of this article is to clarify the nutrient uptake characteristics of C. lanceolata, analyze its nutrient requirement at different growing stages, and draft a rational fertilization procedure. Field experiments with seeds or one-year-old seedlings were conducted at the experimental station of Shandong Agricultural University, China from 2014 to 2016. Nitrogen (N), phosphorus (P) and potassium (K) accumulation of two-year-old C. lanceolata exhibited the same tendency as that of one-year-old plants, but the values were 16.92, 1.65 and 3.69 times higher for N, P and K, respectively. The absorptive ratio of N, P and K was 1:0.93:1.88 for one-year-old C. lanceolata and 1:0.10:0.33 for two-year-old C. lanceolata. The lowest absorptive capacity of N, P and K were found within 60 days after sowing (DAS) for one-year-old C. lanceolata and the highest absorptive capacity were found at 60-90 DAS and 120-150 DSA, respectively. For two-year-old C. lanceolata, the lowest absorptive capacity of N, P and K were within 60 days after transplanting (DAT) and the highest absorptive capacity were fallen within 60-90 DAT and 120-180 DAT. These data could be used to draft a rational fertilization procedure for C. lanceolata. [ABSTRACT FROM AUTHOR]

Silicon(Si) has a significant function in reducing abiotic stresses on plants. pH stress is one of abiotic stresses. We investigated the effects of silicon on maize seedlings under pH stress. The results showed that incorporation of Si (2.0 mM (mmol)) into pH 3.0 increased the growth, chlorophyll and carotenoid contents, decreased catalase, peroxidase and ascorbate peroxidase enzyme activity and malondialdehyde content. The combined treatments with Si (8.0 mM) and pH 3.0 decreased the maize growth compare with the single pH (3.0). Incorporation of Si (2.0 or 8.0 mM) into pH 8.0 were obviously unchanged compare with the single pH (8.0). The combined or single effects of Si (2.0 or 8.0 mM) and pH (3.0 or 8.0) on germination percentage were negligible. The application of Si (2.0 mM) could be a better strategy for improving the plant growth and alleviating low pH stress in soil. [ABSTRACT FROM AUTHOR]

Root chicory is mainly grown in Belgium and the Netherlands with production also elsewhere in Europe, India, and South Africa. The world's crop is worth an estimated US$56.04 million. India and South Africa focus on supplying root chicory to the blend coffee industry. Only limited and variable information is available on the fertilizer requirements of root chicory. Most studies on nitrogen (N) report that chicory in cooler, temperate regions requires 40-75 kg N/ha compared to 200 kg N/ha in warmer areas. Recommended rates for phosphorus (P) range from 0 to 69 kg P/ha. Poor responses to potassium (K) are reported with recommended rates from 0 to 190 kg K/ha. Application rates for sulfur (S) of 10-30 kg S/ha have been suggested. Suitable micronutrient requirements and soil acid saturation and pH values for root chicory have not been published. To establish crop norms a concerted effort is needed to quantify the fertilizer use of root chicory. [ABSTRACT FROM AUTHOR]

The present investigation was undertaken in the on-going long-term fertilizer experiment initiated during 1972 at experimental farm of Department of Soil Science, Himachal Pradesh Agricultural University, Palampur, India. Continuous application of fertilizers either alone or in combination with farmyard manure (FYM)/lime affected different forms of soil acidity (total acidity, total potential acidity, pH dependent acidity, extractable acidity, exchangeable acidity, and non-exchangeable acidity) significantly, in surface and sub-surface layers. Continuous cropping with the application of lime and optimal doses of fertilizers decreased different forms of soil acidity at all the depths, significantly. Highest productivity of wheat and maize was recorded in 100% (nitrogen, phosphorus, potassium) NPK + FYM, which was at par with 100% NPK + lime. Different forms of soil acidity were found to be negatively correlated with wheat and maize yield. Grain and straw/stover yield of wheat and maize showed the highest negative correlation values with non-exchangeable acidity. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is a critical micronutrient for nitrogen (N) fixation in legumes. Low pH limits the availability of Mo, thereby reducing nodulation and N fixation. This study investigates the effect of Mo supplementation on alfalfa nodulation and its correlation with root and shoot biomass in low-pH soil. Three experiments were conducted in the greenhouse, involving 14 genotypes of alfalfa subjected to four different treatments, unlimed low-pH soil (5.2) with Mo applied (lithium (Li)−Mo+), low-pH soil (5.2) without Mo (Li−Mo−), limed soil (pH 7.3) with Mo applied (Li+Mo+), and limed soil (pH 7.3) without Mo (Li+Mo−). Foliar application of Mo resulted in a significant increase in nodule counts in the 14 alfalfa cultivars grown in low-pH soil (5.2) even though to a lesser extent than in limed soil with neutral pH (7.3). The increase in number of nodules correlated positively with plant root weight and upper plant biomass. [ABSTRACT FROM PUBLISHER]

The effects of a low-external-input soil fertility enhancement solution – hereafter termed 'nitrolimigation' were examined, as a preferred technique of applying nitrogen and calcium in the "Acid Sands" soils of southern Nigeria. Two types of nitrogenous fertilizer sources [urea and liquid pig manure (LPM)] and two types of lime {limestone (CaCO3) and hydrated lime [Ca(OH)2]} were used both in greenhouse and in field experiments at varying levels: Urea [CO (NH2)2] 0, 40, 50, 80, 100, 120, and 150 kg ha−1; lime 0, 0.1, 0.3, 0.5, 1.0, 5.0, and 10.0 metric tonnes per hectare (t ha−1) and LPM 0, 30, 60, 90, and 120 t ha−1. The rates were arranged factorially and laid out in randomized complete block design (RCBD). The results indicated that combining lime at 9 t ha−1 and LPM at 90 t ha−1 in irrigation water had significant (P < 0.01) positive effects on the fertility status of the "Acid Sands" soils and growth of okra- Abelmoschus esculentus, the test crop. When urea was combined with hydrated lime, it reduced acidity and provided nutrient balance in the Acid Sands of Calabar. Total nitrogen was significantly (P < 0.01) boosted from 0.05 to 0.11%, base saturation (BS) from 46 to 62%, and exchange acidity was reduced from 2.93 to 1.35 cmol kg−1. Combining urea (46-0-0) at 80 kg ha−1 with lime (CaCO3) at 5 t ha−1 raised the soil pH from 4.4 to 7.1. Exchange acidity was reduced from 0.8 cmol kg−1 to a negligible value, but electrical conductivity was improved from 170.7 to 291.9 μS cm−1. When LPM and lime were combined, organic carbon was increased from 2.75 to 2.93%, BS was increased from 46.72 to 75.19%, and pH was raised from 6.0 to 6.73. Plant height was increased from 9.5 to 16.9 cm while mean number of leaves was also increased from 5.6 to 6.3 only with lower level of lime (3 t ha−1) and LPM at 90 t ha−1. Of the nitrogen and calcium sources, LPM and limestone were better at 120 t ha−1 and 9 t ha−1, respectively, to offset soil acidity, boost nutrient availability, and provide balanced nutrition to arable crops grown on the "Acid Sands" of southern Nigeria. [ABSTRACT FROM AUTHOR]

Applying lime to ameliorate soil acidity has been observed to induce manganese (Mn) deficiency in canola (Brassica napusL.) crops grown on acid sandy soils near Albany and gravelly acid sands of the Great Southern Districts of southwestern Australia. These soils were often Mn-deficient in patches for wheat (Triticum aestivumL.) production when they were newly cleared for agriculture requiring application of Mn fertilizer to ensure grain yields were not reduced by the deficiency. Since then, these soils have acidified and in the 1990s, canola started to be grown on these soils in rotation with wheat and lupins (Lupinus angustifoliusL.). These limed soils may now have become marginal to deficient in Mn for canola production. The effect of liming may change the effectiveness of fertilizer Mn. In addition, the effect of liming on the residual value of Mn fertilizer applied to these soils for canola production is unknown. Therefore, a glasshouse experiment was conducted using Mn deficient sand. Three levels of finely-powdered calcium carbonate were added and incubated in moist soil for 42 days at 22±2°C to produce 3 soils with different pH values [1:5 soil:0.01 M calcium chloride (CaCl2)]: 4.9 (original soil), 6.3, and 7.5. Five Mn levels, as solutions of Mn sulfate, were then added and incubated in moist soil for 0, 50, and 100 days before sowing canola. To estimate the residual value (RV) of incubated Mn for canola production, the effectiveness of the incubated Mn was calculated relative to the effectiveness of Mn applied just before sowing canola (freshly-applied Mn). The RV of the incubated Mn was determined using yield of dried canola shoots, the Mn application level required to produce 90% of the maximum shoot yield, and Mn content in dried shoots (Mn concentration in shoots multiplied by yield of dried shoots). As measured using both yield of dried shoots and Mn content of dried shoots, the residual value of Mn decreased with increasing soil pH and with increasing period of incubation of Mn with moist soil. The critical Mn concentration, for 90% of the total yield of dried canola shoots, was (mg Mn kg−1) ∼17 in youngest mature growth (apex and youngest emerged leaf, YMG), and ∼22 for the rest of dried shoots. These values were similar to current critical values for un-limed soils suggesting critical Mn concentrations remain the same for limed soils. Plant testing of canola is recommended if soils are to be limed to ameliorate soil acidity. When plant tests indicate a high likelihood of Mn deficiency, foliar Mn sprays need to be applied to that crop to ensure Mn deficiency does not reduce grain production that year, and fertilizer Mn needs to be re-applied to the soil when sowing the next crop to reduce the likelihood of Mn deficiency for subsequent crops. [ABSTRACT FROM AUTHOR]

Exchangeable and soluble soil aluminum (Al) is limiting plant growth in many soils worldwide. This study evaluated the effects of increasing rates of dolomite and magnesium carbonate (MgCO3) on Al3+, pH, dissolved organic carbon, cations, anions, and Al speciation on oil palm Delidura× AVROSpisiferaroot growth. Dolomite and MgCO3additions significantly raised linearly soil solution pH, magnesium (Mg2+), nitrate (NO3−) and chlorine (Cl−) concentrations; exponentially decreased the activity of phytotoxic Al species [aluminum (Al3+), aluminum sulfate (Al2SO4), and aluminum fluoride (AlF3)]; and reduced manganese (Mn) concentration and activity. High activity of those species exponentially reduced root dry weight. Optimum oil palm growth was achieved at: <50 μM monomeric Al, < 30 μM Mn, and <0.20 unit of the ratio Al+Mn to calcium (Ca)+Mg. High activity of Al species and Mn in acidic soil solution cause significant reduction of the root growth. Soil acidity alleviation either with dolomite or MgCO3mitigates the toxic effect of Al and Mn. [ABSTRACT FROM PUBLISHER]

Oxisols comprise large soil group in tropical America. These soils are acidic and have low fertility. Use of tropical legume cover crops in cropping systems is an important strategy to improve fertility of these soils for sustainable crop production. Data are limited on nutrient uptake and use efficiency of tropical cover crops under different acidity levels. The objective of our study was to evaluate growth and nutrient uptake parameters of sixteen tropical legume cover crops under three soil pH (5.1, 6.5, and 7.0) of an Oxisol. Shoot dry weight was influenced significantly by pH and cover crop treatments and their interactions, indicating that cover crops used had differential responses to changing soil pH levels. Overall, shoot dry weight decreased when soil pH was raised from 5.1 to 7.0, indicating acidity tolerance of cover crops. Nutrient concentration (content per unit of dry weight), uptake (concentration X dry weight), and nutrient use efficiency (dry weight of shoot per unit of nutrient uptake) varied significantly among cover crops. The variation in nutrient uptake and use efficiency among cover crop species was associated with variation in shoot dry matter production. Significant variation among crop species in dry matter production and low C/N ratios (average value of 14.25) suggest that cover crops which produced higher dry matter yield like white jack bean, gray mucuna bean, black mucuna bean, mucuna bean ana, and lablab are important choices for planting in tropical soils to recover large amount of macro and micronutrients, and to prevent such nutrient leaching in soil plant systems. [ABSTRACT FROM PUBLISHER]

Rape (Brassica napus L.) seedling pot experiments were performed with a red soil treated with goethite which had boron (B) either adsorbed (ad-B-goethite) or occluded (oc-B-goethite). Soil acidity, different forms of manganese in the soils and different elements content of the rape seedlings were determined. It was found that the addition of boron-containing goethite to the soils resulted in increased rape growth, elevated soil pH and decreased exchangeable acidity. Compared with the control, boron-containing goethite elevated the content of exchangeable manganese (Mn) (EXC-Mn), organic matter bound Mn (OM-Mn), reducible oxide Mn (RO-Mn) and residual Mn (RES-Mn) which were difficult to use for plant. Low labile organic matter was significantly correlated with easily reducible oxide Mn (ERO-Mn) (P < 0.01) and RO-Mn (P < 0.05). Middle organic matter and soil pH was significantly (P < 0.05) correlated with RES-Mn. Stepwise regression was used to select the combination of variables that best estimates shoot and root dry weight of rape seedling. Among them, soil pH, EXC-Mn, OM-Mn, RO-Mn and RES-Mn significantly influenced the dry weight of rape seedlings. The addition of boron-containing goethite improved the uptake of iron (Fe), calcium (Ca), magnesium (Mg), and copper (Cu) element and decreased the uptake of Mn and zinc (Zn) element in rape seedling. The results suggested that boron-containing goethite could provide a better soil acidity environment for plant growth; it was also an important agent increasing a part of manganese difficult to use for plant and reducing the activity of soil manganese, which was beneficial to altering rape seedling growth. [ABSTRACT FROM PUBLISHER]

The grasslands of the Appalachian region spread over undulating terrain with high annual precipitation rate which causes a large variation in soil and nutrient factors like water potential (WP), pH, nitrogen (N) and phosphorus (P) levels. There is a need to understand these factors and their interactive effects to design precise agronomic practices for acidic grasslands to maximize production. A pot experiment was conducted with an objective to quantify the effects of WP, pH, N and P rates on herbage accumulation and nutrient recovery of Kentucky bluegrass (Poa pratensis L.) cropping system. Centrally rotatable composite design was applied to study the effects of two levels of WP and five levels each of pH, N, and P fertilizer additions in order to optimize bluegrass herbage mass (yield). WP, pH, and N were significant main effects, as were the interactions WP × pH, WP × N, and pH × N. The yield response function was derived from these four factors. The order of importance for these model parameters based on their effect on herbage accumulation was WP > N > WP × pH > pH >WP × N > pH × N. The optimum levels of WP, soil pH, N, and P rates were predicted for Kentucky bluegrass by using the response surface yield model of this pot study i.e., WP of −422 kPa to −166 kPa, 5.5–6.1 soil pH, 50–68 N mg kg−1, 36–40 P mg kg−1. Concentration (%) of nutrients like N, P, potassium (K), calcium (Ca), and magnesium (Mg) were determined to study the impact of WP, pH, N, and P factors and their interactions on plant nutrient recovery. Main effects like WP, pH, and N levels had significant influence on N and P concentration in plant tissue. K, Ca, and Mg concentrations in plant tissue were significantly affected by WP, pH and their interaction. The results of this greenhouse study imply the necessity to incorporate the information about the variation of soil and nutrient factors in designing precise agronomic practices to low productive acid reclaimed grasslands with undulating topography and high annual precipitation rate. [ABSTRACT FROM AUTHOR]

Alfalfa is one of the most demanding crops in terms of soil fertility. Limestone application is an efficient method of increasing the alfalfa crop yield. This study evaluates the effect of liming on the soil fertility and consequent nutritional state and shoot dry weight yield of alfalfa (Medicago sativa cv. 'Crioula'), grown in pots containing Typic Quartzipisamment soil (savanna phase), in a completely randomized experimental design with repeated measurements over time (cross sections), in two cuttings, with four replicates. The treatments consisted of four limestone rates (0, 3.8, 6.6 and 10.3 t ha-1). The results showed that the greatest estimated shoot dry weight yield in first and second cuttings were obtained with estimated rate of 6.4 t ha-1 and 9.0 t ha-1. The root yield and nitrogen (N) concentration in the nodules was directly related to the soil acidity. In alfalfa, it is necessary at each cutting to closely follow of nutritional state of plants. In tropical edaphoclimatic conditions, the calcium (Ca) saturation in the cation exchange capacity (CEC) to obtain the highest productivity is lower than the values indicated as adequate for soils in temperate climates. [ABSTRACT FROM AUTHOR]

The effect of three arbuscular mycorrhizal (AM) fungi on phosphorus (P) nutrient activation and acquisition by maize from spatially heterogeneous sand was investigated using dual-mesh packages enriched with different P concentrations and compared with non-mycorrhizal cotrols. As would be expected the AM fungi significantly enhanced leaf photosynthetic rate and the biomass and P concentrations in shoots and roots. All three fungi (Glomus intraradices, Glomus mosseae and Glomus etunicatum) displayed the capacity to dissolve inorganic P and promoted P nutrient availability in the packages (P patches). G. etunicatum showed the largest effect comparing with Glomus intraradices and Glomus mosseae, particularly in packages with high concentrations of P. Possible mechanisms involved include the acidification of the P patches by the AM fungi, promotion of the dissolution of the P, and more marked effects of the three fungal isolates with increasing enrichment of P in the patches. Inoculation with G. etunicatum resulted in greater acidification compared to the other two fungi. We conclude that AM fungi can promote P availability by acidifying the soil and consequently exploiting the P in nutrient patches and by facilitating the growth and development of the host plants. [ABSTRACT FROM AUTHOR]

Little is known about the adaptability of rambutan (Nephelium lappaceum) to highly acidic soils rich in aluminum (Al). A 2-yr field study was conducted to determine the effects of various levels of soil Al on dry matter production, plant growth, and nutrient concentration in the leaves of four cultivars of rambutan. Cultivars and the cultivar x year interaction were not statistically significant for most variables measured in the study. Total, leaf, petiole, stem and root dry weights significantly increased at soil Al concentrations ranging from 0.67 cmol kg-1 to 11.0 cmol kg-1. At this range of soil Al, the concentrations of Al and manganese (Mn) in leaf tissue declined sharply. The results of this study demonstrate that rambutan is highly tolerant to acid soils and that tolerance may involve an Al- and Mn- exclusion mechanism. [ABSTRACT FROM AUTHOR]

Aluminum (Al) toxicity is an important factor in limiting crop production. The present study examined the Al alleviation effects on the growth of hybrid (breeding) and clonal (tissue culture) of D × P oil palm seedlings. The experiment was performed using calcium carbonate (CaCO3), and ground magnesium limestone (GML) and magnesium carbonate (MgCO3) as soil-amendments at different rates in Colombia and Malaysia, respectively. The effects of the treatments were evaluated monthly on vegetative variables and visual symptoms. Chlorophyll concentrations were recorded in Malaysia at the fifth month growing stage. The different amendments improved the soil fertility and it was reflected on better performance of shoot and root growth. The chlorophyll content in the frond number 3 for both materials enhanced significantly when Al saturation was low (0-30%). The results from the experiment revealed the importance of neutralization of Al in reducing its toxicity in oil palm. [ABSTRACT FROM AUTHOR]

This research was undertaken to evaluate the influence of zeolite and synthetic aggregates (SRA) produced with acidic red soil and paper waste, on the growth of French marigold (Tagetes patula), which is a popular ornamental plant in Japan. Five different media were studied: SRA only, SRA:Zeolite 3:1, SRA:zeolite 1:1, SRA: zeolite 1:3 and zeolite only. Mixing SRA with zeolite improved the physical and chemical properties of the media such as particle size distribution, bulk density, total porosity, water holding capacity, and pH compared to zeolite. SRA and zeolite at 1:1 gave the best maximum growth parameters of French marigold. Zeolite based mixtures increased the nitrogen (N), potassium (K), magnesium (Mg), and calcium (Ca) concentrations in plant tissues compared to SRA medium. Addition of zeolite led to reduce K leaching from the substrate compared to SRA. SRA and Zeolite at 1:1 can be recommended as a better substrate for French marigold cultivation. [ABSTRACT FROM AUTHOR]

The zinc (Zn) requirements of subterranean clover (Trifolium subteraneaum L.) are well known for the predominantly marginally acidic to neutral sandy soils of southwestern Australia, but the Zn requirements of French serradella (Ornithopus sativus Brot.) and biserrula (Biserrula pelecinus L.), now also grown on these soils, is not known and were investigated in a glasshouse pot experiment. Soil was collected from field plots never treated with Zn or treated once only with 0.5 and 1.0 kg Zn/ha as Zn oxide either in 1983, 1984, 1986, 1990, 1992, 1996, 1997, or 2000. In the pot experiment, six levels of Zn were freshly-applied to samples of soil collected from each Zn treatment of the field experiment, and pots were sown either with subterranean clover cv. 'Dalkeith', French serradella cv. 'Margurita', or biserrula cv. 'Casbah'. The pasture species were defoliated by cutting pasture herbage 3 cm above the soil surface for up to 4 consecutive defoliations. The approximate linear relationship between the level of freshly-applied Zn in the pot experiment required to produce 90% of the maximum yield of dried defoliated herbage (y-axis) and the number of years since Zn was applied in the field (x-axis) was used to project the number of years it took for the 0.5 or 1.0 kg Zn/ha treatments applied in the field to require the same level of freshly-applied Zn to produce 90% of the maximum yield of the nil-Zn treatment in the field. This was 18-19 years for the 0.5 kg Zn/ha treatment and 32-35 years for the 1.0 kg Zn/ha treatment. The range in values was due to differences between legume species and the defoliation treatments, which were not significant. When yields were measured, samples of young growth (YG) were separated from the rest of the defoliated herbage (ROH) and the concentration of Zn in YG and ROH was measured. The concentration of Zn in YG that was related to 90% of the maximum yield of defoliated dried herbage (critical tissue test value) was (mg/kg) 13 for subterranean clover, 17 for French serradella, and 19 for biserrula; respective critical tissue test values for ROH were 19, 24, and 21 mg/kg. The approximate linear relationship between critical Zn concentration in YG (y-axis) and the number of years since Zn was applied in the field (x-axis) was used to project the number of years it took for the 0.5 and 1.0 kg Zn/ha levels applied in the field to reach the same critical tissue test value as the nil-Zn treatment of the field experiment. This was 17-20 years for the 0.5 kg Zn/ha treatment and 31-37 years for the 1.0 kg/ha treatment, which was similar to the 18-19 and 32-35 years projected using yield data. Before sowing the legumes in the pot study soil samples were collected to measure soil test Zn using the DTPA procedure. The critical DTPA soil test Zn, the soil test value that was related to 90% of the maximum yield of defoliated dried herbage, was about 0.20 mg Zn/kg for the 3 pasture legume species and all Zn treatments in the field and pot studies. [ABSTRACT FROM AUTHOR]

Trema micrantha (L.) Blume is a neotropical multipurpose tree species, which could be used in forest restoration and agroforestry. Several cultures, however, require liming to satisfactory yields in acid soils. Therefore, it is important to determine the effect of liming to this native species, in order to include it in agroforestry associations. The aim of this work was to evaluate the morphological changes of T. micrantha, including the calcium oxalate (druses) and cystolith density, as caused by the calcium carbonate (CaCO3) addition. The assay included three treatments: control, pH 5.3; treatment 1, pH 5.5; treatment 2, pH 6.0. The liming reduced the root biomass and increased the shoot biomass. The leaf specific mass and nutrients concentration were not changed. The leaves presented higher density of druses in treatment 2. The cystolith density was not modified, but the cystolith size was increased by the liming. The results indicate liming tolerance in this species. [ABSTRACT FROM AUTHOR]

Soil stresses such as salinity and acidity may adversely affect nitrogen (N)2-fixation. The hypothesis of this study is that soil salinity and acidity inhibit soybean [Glycine max (L.) Merr.] nodulation and N2-fixation due to, at least in part, disruption of the signal exchange process. The objectives were: 1) to determine the effects of stressful soil salinity and acidity on the signal exchange processes between soybean and Bradyrhizobium japonicum, and 2) to determine whether or not the addition of signal molecule genistein to B. japonicum can overcome at least part of the inhibition of nodulation, caused by stressful soil salinity and acidity. Salt (sodium chloride) and sulfur (S) were applied. Genistein (0, 5, and 20μ M) was tested. Genistein addition could partially overcome the salt and acidity stresses by increasing soybean yields up to 21% and 23%, respectively. These novel findings may be very useful for planting soybean under salinity and acidity stresses. [ABSTRACT FROM AUTHOR]

Acidity release as a characteristic of iron (Fe) deficiency stress responses was investigated during early seedling establishment of maize (Zea mays L.), barley (Hordeum vulgare L.), winter wheat (Triticum aestivum L.), and winter rye (Secale cereale L.). Ferric reduction as another characteristic of Fe deficiency stress responses was also investigated in maize. This has previously been considered a process only occurring in iron-stressed dicotyledonous plants. Measurements were made of the Fe efflux from maize endosperm under Fe-deficient and non-limiting conditions. The scutellum of Fe-stressed cereal seedlings (all species investigated) increased agar acidification by 30-40%, while manganese (Mn) or zinc (Zn) stressed seedlings did not demonstrate this reaction. Among the maize genotypes studied ('VIR-7569' and 'VIR-7882'), the Fe-stressed acid release was more prolonged in relatively less Fe-efficient cv. 'VIR-7569.' In maize, the induced enhancement of acid release was accompanied by an increase in Fe efflux from endosperm. Conversely, maize scutellum Fe3 +-reductase activity was not deficiency-dependent on Fe, indicating that enhanced acidity release is a biological phenomenon facilitating Fe supply at early development of graminaceous plants. In cereal seedlings, the coexistence of two marker responses to Fe-deficiency (Strategy I and Strategy II), which are usually typical of different taxonomic groups (dicotyledonous and graminaceous plants) can be regarded as evidence in favour of the hypothesis of common genesis in dicotyledonous and graminaceous plants. [ABSTRACT FROM AUTHOR]

Dissolution of phosphate rocks (PR) in soils requires an adequate supply of acid (H+) and the removal of the dissolved products [calcium (Ca2 +) and dihydrogen phosphate (H2PO4-)]. Plant roots may excrete H+ or OH- in quantities that are stoichiometrically equal to excess cation or anion uptake in order to maintain internal electroneutrality. Extrusion of H+ or OH- may affect rhizosphere pH and PR dissolution. Differences in rhizosphere acidity and solubilization of three PRs were compared with triple superphosphate between a grass (Brachiaria decumbens) and a legume (Stylosanthes guianensis) forage species at two pH levels (4.9 and 5.8) in a phosphorus (P)-deficient Ultisol with low Ca content. The experiment was performed in a growth chamber with pots designed to isolate rhizosphere and non-rhizosphere soil. Assessment of P solubility with chemical extractants led to ranking the PRs investigated as either low (Monte Fresco) or high solubility (Riecito and North Carolina). Solubilization of the PRs was influenced by both forage species and mineral composition of the PR. The low solubility PR had a higher content of calcite than the high solubility PRs, which led to increased soil pH values (> 7.0) and exchangeable Ca, and relatively little change in bicarbonate-extractable soil P. Rhizosphere soil pH decreased under Stylosanthes but increased under Brachiaria. The greater ability of Stylosanthes to acidify rhizosphere soil and solubilize PR relative to Brachiaria is attributed to differences between species in net ion uptake. Stylosanthes had an excess cation uptake, defined by a large Ca uptake and its dependence on N2 fixation, which induced a significant H+ extrusion from roots to maintain cell electroneutrality. Brachiaria had an excess of anion uptake, with nitrate (NO3-) comprising 92% of total anion uptake. Nitrate and sulfate (SO42 -) reduction in Brachiaria root cells may have generated a significant amount of cytoplasmic hydroxide (OH-), which could have increased cytoplasmic pH and induced synthesis of organic acids and OH- extrusion from roots. [ABSTRACT FROM AUTHOR]

Grape tomatoes (Lycopersicon esculentum Mill.) are gaining popularity among consumers because of their flavor, sweetness, potential health benefits, and ease of consumption. Most grape tomatoes are indeterminate varieties. Hence, current production practices (including fertilization rates) may need to be adjusted to larger plants, longer growing seasons, and harvests over several months of the indeterminate varieties. The responses of physical (color and moisture content) and chemical [vitamin C, pH, total titratable acidity (TTA), carotenoids, and soluble solid content (SSC)] parameters for 'Honey Bunch' yellow grape tomato to nitrogen (N) rates were evaluated. In Spring 2005, tomatoes were grown on a Lakeland fine sand in North Florida using plasticulture and N rates of 0, 78, 157, 235, 314, and 392 kg/ha. Tomatoes were harvested fully ripen on 81 and 105 d after transplanting (DAT = 0 on March 24th), and uniform 20-fruit samples were carefully selected. Increasing N rate significantly reduced vitamin C concentration from 44 to 35 mg/100 g and TTA from 0.47% to 0.38% citric acid, but did not significantly affect lutein (mean = 0.26 micro-g/g) and β-carotene (mean = 0.82 micro-g/g) concentrations or color. Response of pulp pH to N rate was significant but within the narrow 4.5 to 4.7 range. Soluble solid contents decreased as N rate decreased for the first harvest (8.1 to 5.6 for 0 to 392 kg/ha of N), but increased for the second harvest (6.9 to 10.1 for 0 to 314 kg/ha of N). Overall, N rate did not have a marked effect on selected quality parameters, suggesting that variety and/or other environmental factors may be more important than N rate in determining chemical composition of grape tomato. [ABSTRACT FROM AUTHOR]

Metal toxicity and soil acidity affect plant growth. A hydroponic experiment was conducted to simulate effects of pH and copper concentration [Cu] on early growth and biomass production of high-yielding rice seedlings ( Oryza sativa L. cv. ‘NIAB 6’). The rice seedlings were allowed to grow in Yoshida nutrient solution with 1 (control), 8, 16, and 32 μM Cu at buffered pH levels of 4.5, 5.0, and 5.5, respectively. Shoot and root growth, leaf chlorophyll content, and root lipid peroxidation and K + leakage of 15-day-old rice seedlings were determined. Results show that [Cu] had significant adverse effects on rice seedlings. Shoot height and root length were reduced by 18%–60% and 7%–69%, respectively, compared with the control, and shoot and root weight decreased by 26%–56%, and 25%, respectively, in response to progressive increases in [Cu]. Similarly, leaf chlorophyll content decreased by 150%–245% compared with the control treatment. Rice seedling roots suffered from significant increases in lipid peroxidation followed by K + leakage (> 8–23 times) in response to increasing [Cu]. Averaged across [Cu], seedling growth and biomass were greater at pH 5.5 than at other pH treatments. In some instances, increasing pH minimized the adverse effects of Cu at low concentrations on rice seedlings. [ABSTRACT FROM AUTHOR]

Six wheat varieties with different tolerance to waterlogging were studied in acidic soil (pH 4.5), neutral soil, and potting mix (pH 6.7–7.8) under controlled conditions. Waterlogging for 49 d reduced shoot dry weight by 48% to 85% compared with drained treatments. The ranking of varieties for waterlogging changed under different soils, and this change explains why waterlogging tolerance of these varieties may vary in different environments. In waterlogged acidic soil, shoot concentrations of aluminum (Al), manganese (Mn), and iron (Fe) increased by two- to 10-fold, and in some varieties they were above critical concentrations compared with plants in drained soil. These elements decreased or remained the same in shoots of plants grown in waterlogged neutral soil. Marginal nitrogen (N) deficiency was induced in most varieties in all soil types. The results support the importance of screening in soils from the target environment for accurate germplasm characterization for waterlogging tolerance. [ABSTRACT FROM AUTHOR]

A maize-melon mixture relayed into a cassava-soybean intercrop was established at Ibadan, Nigeria, between 1995 and 1997 in order to study the changes in soil-nutrient status, that occurred due to soybean intercropping and residue incorporation. The experiment was conducted on a Kanhaplic Haplustalf soil. Soybean was planted in drills between cassava rows after harvesting maize and melon. Soybean stover was recycled into half of the soybean plots. Cassava yield was reduced by about 16% with soybean intercropping without the residue incorporation and by about 11% with incorporation of the crop residue. Soil pH was significantly reduced from an initial 6.0 to 5.7 with soybean intercropping. Organic matter was drastically reduced from an initial 31.0 g kg -1 to 5.3 g kg -1 with sole cassava cropping, and to 10.1 g kg -1 with soybean intercropping and incorporation of crop residue. Total nitrogen (N) was also significantly reduced to about 0.4 g kg -1 from an initial content of 1.8 g kg -1 , while the available phosphorus (P) was increased from 1.8 to an average of 4.0 mg kg -1 . The exchangeable potassium (K) and effective cation-exchange capacity (ECEC) were not significantly affected. [ABSTRACT FROM AUTHOR]

As Brachiaria hybrid cv. 'Mulato' has adapted to acid soils with extremely low phosphorus (P) contents, its low-P-tolerance mechanisms were investigated and compared with those of wheat (Triticum aestivum L.) and rice (Oryza sativa L. cv. 'Kitaake'). Among the three plant species, the highest P-use efficiency (PUE) in low-P soil was recorded in the Brachiaria hybrid, which increased remarkably under P-deficiency and soil acidity, while P-deficiency had less effect on the PUE of wheat and rice. As exudation of organic acid anions from roots is considered to be one of the most important mechanisms of adaptation to low-P soil, the role of phosphoenolpyruvate carboxylase (PEPC), which is closely related to organic acid metabolism and Pi recycling in C3 plants, was studied. As expected, the PEPC activity of the Brachiaria hybrid (C4 plant) leaves was 51- to 129-fold higher than that estimated for wheat and rice (both C3 plants). PEPC activity in leaves and roots of the Brachiaria hybrid increased up to two-and three-fold, respectively, and decreased the malate-inhibition ratio in leaves in response to P-deficiency. However, PEPC activity and malate-inhibition ratio were less affected in wheat and rice under P-deficiency. The Brachiaria hybrid synthesized higher amounts of organic acids (e.g., oxalate and fumarate) in leaves, especially under P-deficiency. Results from these experiments indicate that PEPC activated in the Brachiaria hybrid under low-P and low-pH conditions may contribute to the plant's greater adaptation to tropical acid soils with P-low availability. [ABSTRACT FROM AUTHOR]

Pigeonpea [Cajanus cajan (L.) Millsp.] is a legume with potential as an alternative summer crop in the U.S. Southern Coastal Plain. It has low fertilizer and pesticide requirements, and is used for both animal feed and human food. Southern coastal plain soils are acidic and phosphorus (P) deficient before liming and fertilization. Under those conditions, pigeonpea is limited in its ability to symbiotically fix atmospheric nitrogen (N2). Calcium silicate application can reduce the adverse effects of soil acidity and also enhance the availability of P in such soils. The effects of calcium silicate on P availability and the effects of Rhizobiuin inoculation on the growth of pigeonpea on a Greenville soil from the coastal plain of Georgia were investigated in laboratory and greenhouse experiments. Both silicon (Si) and P applications significantly increased the growth of pigeonpea. Optimum fresh and dry shoot weights, plant-available water, shoot height, nitrogen (N) and P contents, and P:manganese (Mn) ratios were found when 1.96 g Si/pot (4.48 t Si/ha) was applied as calcium silicate. High levels of plant Mn concentrations were reduced by such application. Application of 0.1 g P/pot (39 kg P/ha) produced the optimum fresh and dry shoot weights, plant water content, and shoot height. Inoculation had no effect on plant growth. There were no interactions for growth among Si, P, and inoculation. Increased growth due to Si application was adduced to increased available N and P and reduced levels of Mn. Applied Si also increased plant-available water, which enhanced leaf erectness-an important factor in light interception and therefore in growth. Low soil-available P was increased by fertilizer P, resulting in increased growth. Although Si is not an essential element, calcium silicate improved the growth of pigeonpea grown on this low pH soil. [ABSTRACT FROM AUTHOR]

Soil acidity is one of the limiting factors affecting the production and sustainability of pastures and crops in many parts of the world. An on-farm experiment was conducted in Australia to investigate the cultivar variation in alfalfa (lucerne) (Medicago sativa L.) with respect to soil acidity and response to applied lime. The experimental site was a brown sandy clay loam with a soil pH of 4.8 (1:5 calcium chloride). Ten cultivars (Hunter River, Hunterfield, Sceptre, Aurora, Genesis, Aquarius, Venus, PL90, PL55, and breeding line Y8804) were tested at two levels of lime (0 and 2 t ha-1). Lime application significantly increased the root growth, nodulation, leaf retention, leaf to stem ratio, herbage yield, and crude protein content of alfalfa. Liming had a significant effect on elemental composition of alfalfa shoots. Aluminum (Al) concentration was reduced from 93 mg kg-1 DM in nil lime treatment to 45 mg kg-1 DM in +lime treatment. Similarly, manganese (Mn) and iron (Fe) shoot concentrations were reduced from 74 mg kg-1 DM and 92 mg kg-1 DM to 59 mg kg-1 DM and 76 mg kg-1 DM, respectively. Liming significantly improved the calcium (Ca) concentration of shoots, while there was a little effect on phosphorus (P) and zinc (Zn) concentrations of alfalfa shoots. Cultivars had differential response to lime application. Response to lime application was greater in Y8804 and Aurora alfalfa where yield increased by 32% and 31%, while yield increase was 11–22% in other cultivars. Cultivars also differed significantly in root growth, nodulation, leaf drop, leaf to stem ratio, crude protein content, and elemental composition of shoots. Cultivars with better performance in no liming treatment had comparatively lower shoot Al, Mn, and Fe concentrations compared with other cultivars. [ABSTRACT FROM AUTHOR]