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Endophytic bacteria of halophytic plants play essential roles in salt stress tolerance. Therefore, an understanding of the true nature of plant—microbe interactions under extreme conditions is essential. The current study aimed to identify cultivable endophytic bacteria associated with the roots and shoots of Seidlitzia rosmarinus Ehrenb. ex Boiss. grown in the salt-affected soil in Uzbekistan and to evaluate their plant beneficial traits related to plant growth stimulation and stress tolerance. Bacteria were isolated from the roots and the shoots of S. rosmarinus using culture-dependent techniques and identified by the 16S rRNA gene. RFLP (Restriction Fragment Length Polymorphism) analysis was conducted to eliminate similar isolates. Results showed that the isolates from the roots of S. rosmarinus belonged to the genera Rothia, Kocuria, Pseudomonas, Staphylococcus, Paenibacillus and Brevibacterium. The bacterial isolates from the shoots of S. rosmarinus belonged to the genera Staphylococcus, Rothia, Stenotrophomonas, Brevibacterium, Halomonas, Planococcus, Planomicrobium and Pseudomonas, which differed from those of the roots. Notably, Staphylococcus, Rothia and Brevibacterium were detected in both roots and shoots, indicating possible migration of some species from roots to shoots. The root-associated bacteria showed higher levels of IAA (indole-3-acetic acid) synthesis compared with those isolated from the shoots, as well as the higher production of ACC (1-aminocyclopropane-1-carboxylate) deaminase. Our findings suggest that halophytic plants are valuable sources for the selection of microbes with a potential to improve plant fitness under saline soils.

The broad bean (Vicia faba L.) originated in the Near East, and is cultivated around the world, however, its cultivation is affected by drought stress in several central growing regions of the globe. The present study was designed to determine the effect of biochar on bean plant growth, acquisition of nitrogen (N), phosphorus (P), and potassium (K) and on soil nutrient contents under drought and irrigated conditions. Pyrolysis char from maize (MBC) at 2 and 4% concentrations was used for pot experiments. The shoot and/or root biomass of bean grown in soil amended with 2 and 4% MBC under irrigated condition was increased. Furthermore, increased nodule numbers of bean grown at 4% MBC amendment was observed under both irrigated and drought conditions. P and K uptake of plants under drought conditions increased by 14% and 23% under 2% MBC amendment, and by 23% and 34% under 4% MBC amendment as compared to plants grown without biochar application, respectively. This study demonstrated beneficial effects of biochar produced from maize on growth and nutrient uptake of broad bean, by improving the nodule formation and soil nutritional contents in a sandy loam soil.

Introduction The practice of co-applying chemical fertilizers (CF) with organic inputs (OIs) as a soil amendment is still low in Ghana, although it has the potential to improve crop yield and soil productivity. Objectives In a two-year study, we evaluated the effects of co-applying contrasting OIs with and without CF on maize yield and soil chemical and microbial composition. Methods Aboveground biomasses of Centrosema pubescens (CEN), Pueraria phaseoloides (PUE), and Zea mays (MZE) were amended to an acrisol at 4 t ha−1 season−1. The combined treatments (CEN+, PUE+, and MZE+) were fertilized with basal NPK 15:15:15 at 40 kg N ha−1, followed by topdressing with [(NH4)2SO4] at 50 kg N ha−1. Sole OI inputs (CEN, PUE, and MZE) did not receive any CF inputs. The controls (CON− and CON+) received 0 and 90 kg N ha−1 season−1. Results The results showed that either sole OIs except for MZE or its combination with CF improved grain yield compared to the CON. Grain yield ranged from 2.1 t ha−1 to 2.6 t ha−1 in the first season versus 0.8 t ha−1 to 1.7 t ha−1 in the second. The MZE+ and CEN+ treatments showed the highest mean grain yields and were similar to CON+. Although CF addition to OIs improved grain yield in all treatments, negative interaction was observed for CEN and PUE as opposed to a positive interaction in the MZE treatment. Co-application of CF with OIs on dissolved organic carbon and nitrogen (DOC) and (EON) dynamics depended on seasonal soil moisture and sampling time. Moreover, co-application of CF with OIs enhanced microbial biomass in CEN but showed minimal and suppressive effects on MZE and PUE amendments, respectively. Conclusion Overall, the increased grain yield in MZE+, CEN+ and CON+ was attributable primarily to the CF addition. Thus, long term evaluations are recommended for sustainable utilization of MZE and CEN given their minimal responses in the short term in the presence of CFs.

The interaction effects of different fertilisation regimes and weather variability on crop yield is a challenge that requires long-term investigation. Therefore, yield data for spring barley (SB) i...

Sulfur (S) and Nitrogen (N) metabolisms in plants are interacted and it is known that S deficiency decrease N absorption and metabolism. In leguminous plants S deficiency also decreases N2 fixation by rhizobia in the nodules. Deep placement of a controlled-release N fertilizer is a good method to provide nitrogen to soybean without inhibiting N2 fixation; thus, it was hypothesized that this method is able to provide nitrogen effectively to sulfur-deficient soybean plants. In this study effects of deep placement of coated urea on S-N physicological interaction, growth and productivity in soybean plants were examined using pot experiments. Soybean plants were grown with sulfate concentrations of 30, 100, or 1000 μM, with or without deep placement of coated urea. Shoot weights at the developing stage were not affected by S deficiency. SPAD values of leaves during the flowering stage decreased with S deficiency and increased with the deep placement of coated urea. S deficiency decreased seed weight per plant at the harvesting stage, but this decrease was attenuated by the deep placement of coated urea. N and S content in shoots at the developing stage increased with the deep placement of coated urea, whereas in seeds, only the N content increased. N2 fixation activity based on the relative ureide-N content in xylem sap indicated that the deep placement of coated urea did not inhibit N2 fixation activity at the early flowering stage. Without deep placement of coated urea, the relative ureide-N content decreased under S deficiency at the seed filling stage. These results suggest that the deep placement of coated urea is an efficient method to supply N to support soybean yield under S deficiency. Abbreviations: Deep+: with deep placement of coated urea; Deep–: without deep placement of coated urea

Increasing soil salinisation is an environmental stressor that causes significant reduction in crop productivity and increases the risk of farming and hence reduces the cultivated land area. For these reasons, soil salinisation is considered to be one of the most serious problems threatening food security. In the north central coastal region of Vietnam, saltwater intrusion in the dry season is a major concern for rice farming. To better understand the adverse impacts of soil salinisation in crops, this study investigates impacts of salinity on mean and variability of rice yields in four communes of Thua Thien Hue Province. In addition, the study looks at possible changes in the portfolio of rice cultivars, which would offer farmers the potential to increase yields and decrease yield variability simultaneously. Results clearly showed that salinity had an impact on yield levels, resulting in an average yield loss of 0.164 tonnes/ha from mean yield levels per unit increase of electrical conductivity. The results did not show that increasing salinity contributes to an increase in variability of yields, but points to the fact that saline water intrusion may lead to consistently lower yields in the study area. Results also indicate that farmers with smaller, scattered plots could be disproportionately affected by salinity and be less capable of managing the saline soils. In addition, saline conditions may also drive the increased use of environmentally damaging inputs, such as pesticides, to offset the decline in yields and thereby potentially lead to a vicious circle. Utilisation of an optimised portfolio of rice varieties that combine profit maximisation and risk reduction reveals that farmers can benefit from revised portfolios of existing varieties at initial salinity levels, but need to include salt-resistant varieties in the portfolio as salinity levels increase.

The need to preserve and enhance biodiversity in agricultural landscapes is widely accepted. In the case of maize, there is a chance to combine production and biodiversity in the same field by microsegregation: wildflowers are sown between the future maize rows after harvest of the last main crop. These wildflower strips provide flowers and vegetation structure within fields and favour biodiversity without losing production area. The system is based on reliable cropping techniques such as strip-till, underground fertilization and band spraying, allowing the poor habitat quality of conventional maize caused by late soil tillage and lack of vegetation structure to be overcome. Field trials at two sites in Germany were conducted, testing the agricultural feasibility, ecological efficiency and yield impacts. The results show the successful establishment of the wildflower strips between the maize rows. Flowering diversity was up to eight times higher than in conventional maize crop stands. Positive implications for pollinators and ground beetles could be proved. The habitat quality for the skylark could be improved by a factor of 2–3, to nearly normal reproduction of the population. A yield reduction of at least 30% was observed. Further investigations will address this yield gap. Furthermore, the management of spontaneous weeds needs further improvement.

In order to optimize relative seed frequency of intercropped pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.), to achieve maximum relative yields and to gain a better understanding of interactions between yield formation and accumulation of nitrogen (N) and sulphur (S) under field conditions, field trials were conducted at several sites in Germany on long-term (>10 years) organically cultivated arable land in two years. These field trials investigated the effects of intercropping and the calculation of relative seed frequency in pea-barley mixtures to achieve maximum relative seed and shoot yields, as well as N and S accumulation. Under the given environmental conditions, a high degree of complementarity over a wide range of growing resources achieved relative total seed yields (RYT) of 1.35 and an increased N and S accumulation in the shoot of the mixture of 35% and 29% compared to the means of the pure stands of pea and spring barley. The increased complementarity of S resources (RYT S shoot = 1.29) was obviously a consequence of promoted vegetative growth caused by the increased complementarity of N resources of the cereal-legume mixture. To achieve the maximum seed yield and maximum N and S accumulation in substitutive mixtures of pea and spring barley, a relative seed frequency of 42%–88% pea seeds to 12%–58% spring barley seeds of their monocrop seeding rate has been calculated to be optimal. The availability of N in the soil of the respective environment, quantified by N accumulation in barley shoots, did not influence optimal relative seed frequency of the intercrop.

Two-year field experiments were conducted at Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu, India, to evaluate the effect of continuous flooding (CF) and alternate wetting and drying (AWD) irrigation strategies on rice grain yield and greenhouse gas emissions from double-cropping paddy rice. Field observation results showed that AWD irrigation was found to reduce the total seasonal methane (CH4) emission by 22.3% to 56.2% compared with CF while maintaining rice yield. By using the observed two-year field data, validation of the DNDC-Rice model was conducted for CF and AWD practices. The model overestimated rice grain yield by 24% and 29% in CF and AWD, respectively, averaged over the rice-growing seasons compared to observed values. The simulated seasonal CH4 emissions for CF were 6.4% lower and 4.2% higher than observed values and for AWD were 9.3% and 12.7% lower in the summer and monsoon season, respectively. The relative deviation of simulated seasonal nitrous oxide (N2O) emissions from observed emissions in CF were 27% and &minus, 35% and in AWD were 267% and 234% in the summer and monsoon season, respectively. Although the DNDC-Rice model reasonably estimated the total CH4 emission in CF and reproduced the mitigation effect of AWD treatment on CH4 emissions well, the model did not adequately predict the total N2O emission under water-saving irrigation. In terms of global warming potential (GWP), nevertheless there was a good agreement between the simulated and observed values for both CF and AWD irrigations due to smaller contributions of N2O to the GWP compared with that of CH4. This study showed that the DNDC-Rice model could be used for the estimation of CH4 emissions, the primary source of GWP from double-cropping paddy rice under different water management conditions in the tropical regions.

The effects of biochar on plant growth vary depending on the applied biochar type, study site environmental conditions, microbial species, and plant&ndash, microbial interactions. The objectives of the present study were therefore to assess 1) the response of growth parameters of lupin and root disease incidence to the application of three biochar types in a loamy sandy soil, and 2) the role of endophytic bacteria in biological control of root rot disease incidence in lupin after the amendment of soil with different biochar types. As biochar types we tested (i) hydrochar (HTC) from maize silage, (ii) pyrolysis char from maize (MBC), and (iii) pyrolysis char from wood (WBC) at three different concentrations (1%, 2%, and 3% of char as soil amendments). There were no significant effects in lupin shoot and root growth in soils amended with WBC at any of the concentrations. MBC did not affect plant growth except for root dry weight at 2% MBC. HTC char at 2% concentration, significantly increased the root dry weight of lupin by 54&ndash, 75%, and shoot dry weight by 21&ndash, 25%. Lupin plants grown in soil amended with 2% and 3% WBC and MBC chars showed 40&ndash, 50% and 10&ndash, 20% disease symptoms, respectively. Plants grown in soil without biochar and with HTC char were healthy, and no disease incidence occurred. Pseudomonas putida L2 and Stenotrophomonas pavanii L8 isolates demonstrated a disease reduction compared to un-inoculated plants under MBC and WBC amended soil that was infested with Fusarium solani.

Biochar has been used widely as a soil amendment to improve plant growth, nutrient acquisition, stress tolerance and to improve soil biological, chemical and physical properties. Several studies suggest biochar as a carrier for bacterial inoculants under various climatic and environmental conditions because of the properties that favour microbial life. Biochar is rich in organic carbon, contains nutrients, such as N, P, K, has a high porosity, and high water-holding capacity. In this review, we synthesise results on the effectiveness of biochar as a carrier for inoculum in pot and field conditions. Biochar as a carrier supported a high survival rate of introduced bacteria and significantly increased colonization in the plant rhizosphere. Soil microbes are known to play an essential role in soil biochemical processes, and nutrient cycles; improve plant stress tolerance, and nutrient acquisition through their ability to fix atmospheric nitrogen, solubilize phosphate, or by enhancing decomposition of plant residues. Moreover, biochar-based inoculants increased root and shoot biomass, nodulation and nutrient uptake of plants in pot and field experiments. Biochar-based inoculants were also effective in enhancing plant growth and grain yield in pot and field experiments. These studies demonstrate that biochar can be considered as a suitable carrier or formulation of bacterial inoculants even in hostile environments and might contribute to replace other commercially used materials successfully. Biochar-based rhizobial inoculants can significantly improve the symbiotic performance of legumes with rhizobia which may reduce N fertilizer demand and thus promote the sustainability of crop production.

To investigate the interrelationships among biochar, soil nutrients, and soybean plant growth in more detail, the root nodulation response of soybean (Glycine max L.) to biochar application was analyzed in a field study. We further examined the biochar effect on soil phosphatase activity to elucidate the relationships among biochar, phosphatase activity, and plant phosphorus uptake. Soybean was planted in a sandy field wherein the biochar and irrigation conditions were considered the two treatment factors. In our result, irrigation increased the pod number and plant height by 20.7% and 11.1%, respectively. Irrigation reduced the shoot and root dry matter content by 67.9% and 75.1%, respectively. The nodule number increased by 37% due to biochar addition under irrigated conditions. The soil carbon concentration was elevated by 13.4% with biochar application under rainfed conditions. Acid phosphomonoesterase (APM) was increased by 21.8% in the biochar-incorporated plots under the irrigated condition. Principal component analysis and redundancy analysis suggested that biochar application enhanced the relationships between the nodule number and soil potassium and magnesium concentrations. The correlation between soil sulfur content and nodule number was eliminated by biochar application. APM activity was associated with higher shoot and root phosphorus content and shoot dry weight after biochar application.

Rainfed agriculture constitutes around 80% of the world&rsquo, s agricultural land, achieving the lowest on-farm crop yields and greatest on-farm water losses. Much of this land is in developing countries, including sub-Saharan Africa (SSA), where hunger is chronic. The primary constraint of rainfed agriculture&mdash, frequently experienced in SSA&mdash, is water scarcity, heightened by the unpredictability of season onset, erratic rainfall, as well as the inability of farmers to provide adequate soil and crop management. Farmers react differently to constraints, making a variety of choices&mdash, including the timing of planting, type of land cultivation, fertilization, and scattered fields, among many others. Limited information is available on the combined effects of these strategies for improving crop yield and water use efficiency (WUE). An experiment was co-conducted with farmers over four consecutive rainy seasons (2014&ndash, 2018) in Tanzania, to evaluate these strategies for single and joint effects in improving yield and WUE on rainfed pearl millet (Pennisetum glaucum (L.) R.Br.). The treatments used were flat cultivation both without and with microdosing, as well as tied ridging without and with microdose interaction, with different planting dates depending on farmers&rsquo, decisions. Results show that farmers react differently to the early, normal, or late onset of the rainy season, and cumulative rainfall during its onset, which affects their decisions regarding planting dates, yield, and WUE. Microdose fertilization increases both the yield and WUE of pearl millet significantly, with greater effects obtained using tied ridging compared to flat cultivation. For low-income smallholder farmers in a semi-arid agroclimate, using tied ridging with microdosing during early planting is an effective response to spatiotemporal rainfall variability and poor soils.

The use of plant materials as soil amendments is an uncommon practice amongst major farming communities in Ghana, although it is necessary for soil fertility improvement. An examination of the effects of soil amendments is necessary to encourage the use of under-utilized organic resources in Ghana. Thus, a field experiment was conducted using 8 different tropical plant materials mixed with chicken manure as soil amendments for growth of tomato as a test crop. The plant materials included Leucaena leucocephala, Centrosema pubescens, Sesbania sesban, Gliricidia sepium, Mucuna pruriens, Pueraria phaseoloides, Azadirachta indica, and Theobroma cacao. There were two other treatments: one with equivalent amounts of chemical fertilizers and the other with no-fertilizer input (control). Plant materials were mixed with chicken manure to obtain a uniform carbon-to-nitrogen (C:N) ratio of 5:1. Except the no-fertilizer control, all treatments received the same amount of nitrogen (N). To clarify the decomposition pattern of the plant materials in soil, an incubation experiment was conducted using only the plant materials before the field experiment. The Gliricidia treatment released significantly more mineral N than the other plant materials in the incubation experiment. However, the tomato fruit yield was not enhanced in the Gliricidia treatment in the field experiment. The known quality parameters of the tested plant materials, such as total N, total carbon (C), C:N ratio, and total polyphenols, had minimal effects on their mineralization dynamics. Azadirachta showed the best synergistic effect with chicken manure through significantly increasing soil microbial biomass and fruit yield of tomato. This result provides insights into the possible adoption of Azadirachta in combination with chicken manure as a soil amendment in small-scale agricultural holdings.

Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for agriculture. We have used crop-level yields, modeled heterotrophic respiration (Rh) and land use data to estimate spatio-temporal changes in regional scale net primary productivity (NPP), plant C inputs, and net biome productivity (NBP) in northern Japan's arable croplands and grasslands for the period of 1959-2011. We compared the changes in C stocks derived from estimated NBP and using repeated inventory datasets for each individual land use type from 2005 to 2011. For the entire study region of 2193 ha, overall annual plant C inputs to the soil constituted 37% of total region NPP. Plant C inputs in upland areas (excluding bush/fallow) could be predicted by climate variables. Overall NBP for all land use types increased from -1.26MgCha(-1)yr(-1) in 1959-0.26 Mg Cha(-1)yr(-1) in 2011. However, upland and paddy fields showed a decreased in NBP over the period of 1959-2011, under the current C input scenario. From 1988, an increase in agricultural abandonment (bush/fallow) and grassland cover caused a slow increase in the regional C pools. The comparison of carbon budgets using the NBP estimation method and the soil inventory method indicated no significant difference between the two methods. Our results showed C loss in upland crops, paddy fields and sites that underwent land use change from paddy field to upland sites. We also show C gain in grassland from 2005 to 2011. An underestimation of NBP or an overestimation of repeated C inventories cannot be excluded, but either method may be suitable for tracking absolute changes in soil C, considering the uncertainty associated with these methods.

To compare how different analytical methods explain crop yields from a long-term field experiment (LTFE), we analyzed the grain yield of winter wheat (WW) under different fertilizer applications in M&uuml, ncheberg, Germany. An analysis of variance (ANOVA), linear mixed-effects model (LMM), and MP5 regression tree model were used to evaluate the grain yield response. All the methods identified fertilizer application and environmental factors as the main variables that explained 80% of the variance in grain yields. Mineral nitrogen fertilizer (NF) application was the major factor that influenced the grain yield in all methods. Farmyard manure slightly influenced the grain yield with no NF application in the ANOVA and M5P regression tree. While sources of environmental factors were unmeasured in the ANOVA test, they were quantified in detail in the LMM and M5P model. The LMM and M5P model identified the cumulative number of freezing days in December as the main climate-based determinant of the grain yield variation. Additionally, the temperature in October, the cumulative number of freezing days in February, the yield of the preceding crop, and the total nitrogen in the soil were determinants of the grain yield in both models. Apart from the common determinants that appeared in both models, the LMM additionally showed precipitation in June and the cumulative number of days in July with temperatures above 30 &deg, C, while the M5P model showed soil organic carbon as an influencing factor of the grain yield. The ANOVA results provide only the main factors affecting the WW yield. The LMM had a better predictive performance compared to the M5P, with smaller root mean square and mean absolute errors. However, they were richer regressors than the ANOVA. The M5P model presented an intuitive visualization of important variables and their critical thresholds, and revealed other variables that were not captured by the LMM model. Hence, the use of different methods can strengthen the statement of the analysis, and thus, the co-use of the LMM and M5P model should be considered, especially in large databases involving multiple variables.

Hydrochar is rich in nutrients and may provide a favorable habitat or shelter for bacterial proliferation and survival. Therefore, in this study, we investigate the efficiency of a hydrochar-based rhizobial inoculant (Bradyrhizobium japonicum) on the symbiotic performance of soybean under both greenhouse and field conditions. There were positive and significant effects of hydrochar-based inoculation on the root and shoot growth of soybean as compared to uninoculated plants grown under irrigated and drought conditions. The drought stress significantly inhibited the symbiotic performance of rhizobia with soybean. Soybean inoculated with hydrochar-based B. japonicum produced twofold more nodules under drought stress conditions as compared to plants inoculated with a commercial preparation/inoculant carrier B. japonicum (HISTICK). The N concentration of inoculated plants with hydrochar-based B. japonicum was by 31% higher than that of un-inoculated plants grown in pots and by 22% for HISTICK. Furthermore, the soybean treated with hydrochar-based B. japonicum showed higher grain yield of 29% under irrigated conditions and 40% higher under rainfed condition compared to un-inoculated plants. In conclusion, the obtained results proved the potential of hydrochar-based B. japonicum inoculant for soybean in terms of increased symbiotic performance and agronomic traits, especially under rainfed conditions.

Intensive manure application is a significant source for environmental nitrogen fluxes. In this study, we evaluated the effect of intensive manure management on nitrogen(N) loading and recommended the critical livestock density for the typical paddy rice and corn cropping systems in a dairy farming watershed using a calibrated DNDC model. The results indicated that a significant amount of N was lost as N2O emission and NO3−-N leaching under current intensive manure application. As the number of dairy cattle increased, soil N2O emissions and NO3−-N leaching increased with a rate of 2.11 kg N LU−1 yr-1 and 39.7 kg N LU−1 yr-1, respectively. Changing manure to chemical fertilizer, NO3−-N leaching was trend to increased. If decreasing fertilizer rate too low, crop N decreased and the soil N was significantly deficit. Integrated all the analysis, we recommended that critical N application rate was approximately 150–300 kg N ha−1 yr−1 for corn system and 100–250 kg N ha−1 yr−1 for paddy rice system, respectively. The critical livestock density in these cropping systems is 0.7–3.0 LU ha−1 yr−1 for dairy cattle manure using. Based on these recommendations, the crop N use efficiency(NUE) could increase from 17 % to 65 % for corn cropping and from 59 % to 75 % for paddy rice cropping. To mitigation the significant environmental nitrogen, the current livestock densities need to decrease by 40–60 % in the studied region or the major crop system needs to be changed from one season rice to double rotation cropping system.

Efforts to improve soil productive capacity aimed at boosting crop production in the Northern Ghana has primarily focused on field-based experiments with little documentation on farmer practice and local indigenous knowledge of soil management. A sample group of 114 farmers from five farming communities in the Guinea Savannah was interviewed to evaluate their indigenous knowledge of crop production practices in the context of soil health, fertilization management, and crop yield. Data were collected using semi-structured interviews and responses for each category were calculated using simple proportions. Farmers’ fertilization practice was primarily influenced by fertilization resource availability and crop yield response. The results showed that inorganic fertilization was the commonest fertilization type among farmers. Farmer local indicators of soil health were predominantly limited to visually observable signs such as presence or absence of indicator plants, growth vigor of plants, soil color, and tilth, texture, and compaction. Non-tactile and visible indicators, notably soil chemical composition and presence of soil microorganisms, was rarely used. The listed indicators were congruent with scientific reports, although some knowledge gaps, particularly on the use of indicator plants, were identified. The use of indicator plants as determinants of healthy or non-healthy soils appeared to be influenced by the ease of control of weeds, its utilitarian benefits, benefits to the soil, and threats on cultivated crops. Famers were well informed about the decreasing crop yield. Fertilization practices and limitations in soil management practices with proposed capacity building approaches aimed at enhancing productive capacities of cultivated farmlands are discussed. Japan Society for the Promotion of Science

To analyze the effects of tillage (no-tillage, plow tillage), irrigation (rainfed, irrigated), and crop rotation (continuous maize, 4-year crop rotation) and their development, we conducted a field experiment over 9 years under sandy soil conditions in northeastern Germany. The generalized linear model showed that tillage, irrigation and crop rotation jointly explained approximately 35% of the total variance. Irrigation and crop rotation significantly positively influenced maize biomass yield started immediately in the first years in 2008 and 2011 respectively, while tillage started to significantly positively affect yield starting from the fourth year. In general, irrigation had the most relative importance as a management factor compared to the importance of tillage and crop rotation. Crop rotation with legumes increased soil nitrogen and carbon content and led to a higher yield than continuous maize 11.1 dt ha−1 y−1 in average. Furthermore, the significant effect of crop rotation on the yield of the following crop (maize) continued after 2 cycles of a 4-year crop rotation. A significant influence of the 2-way interactions between rotation, tillage and irrigation was only found in extremely dry years. It can be concluded that (i) the negative influence of no-tillage becomes noticeable after 3 years, leading to significantly lower yield compared to plow tillage; (ii) under the sandy soil and dry conditions, irrigation significantly increases yields and is the most important factor compared to tillage and crop rotation; and (iii) crop rotation significantly increases and maintains maize yield under both plowed and irrigated conditions.

Drought and heat-tolerant crops, such as Pearl millet (Pennisetum glaucum), are priority crops for fighting hunger in semi-arid regions. Assessing its performance under future climate scenarios is critical for determining its resilience and sustainability. Field experiments were conducted over two consecutive seasons (2015/2016 and 2016/2017) to determine the yield responses of the crop (pearl millet variety &ldquo, Okoa&rdquo, ) to microdose fertilizer application in a semi-arid region of Tanzania. Data from the experiment were used to calibrate and validate the DSSAT model (CERES Millet). Subsequently, the model evaluated synthetic climate change scenarios for temperature increments and precipitation changes based on historic observations (2010&ndash, 2018). Temperature increases of +0.5 to +3.0 &deg, C (from baseline), under non-fertilized (NF) and fertilizer microdose (MD) conditions were used to evaluate nine planting dates of pearl millet from early (5 December) to late planting (25 February), based on increments of 10 days. The planting date with the highest yields was subjected to 49 synthetic scenarios of climate change for temperature increments and precipitation changes (of &minus, 30% up to +30% from baseline) to simulate yield responses. Results show that the model reproduced the phenology and yield, indicating a very good performance. Model simulations indicate that temperature increases negatively affected yields for all planting dates under NF and MD. Early and late planting windows were more negatively affected than the normal planting window, implying that temperature increases reduced the length of effective planting window for achieving high yields in both NF and MD. Farmers must adjust their planting timing, while the timely availability of seeds and fertilizer is critical. Precipitation increases had a positive effect on yields under all tested temperature increments, but Okoa cultivar only has steady yield increases up to a maximum of 1.5 &deg, C, beyond which yields decline. This informs the need for further breeding or testing of other cultivars that are more heat tolerant. However, under MD, the temperature increments and precipitation change scenarios are higher than under NF, indicating a high potential of yield improvement under MD, especially with precipitation increases. Further investigation should focus on other cropping strategies such as the use of in-field rainwater harvesting and heat-tolerant cultivars to mitigate the effects of temperature increase and change in precipitation on pearl millet yield.

To investigate the influence of gypsum application on methane (CH4) emission from paddy rice soil affected by saline irrigation water, two pot experiments with the rice cultivation were conducted. In pot experiment (I), salinity levels 30 mMNaCl (S30) and 90 mMNaCl (S90), that showed maximum and minimum CH4 production in an incubation experiment, respectively, were selected and studied without and with application of 1 Mg gypsum ha−1(G1). In pot Experiment (II), CH4 emission was investigated under different rates of gypsum application: 1 (G1), 2.5 (G2.5), and 5 (G5) Mg gypsum ha−1 under a non-saline and saline condition of 25 mMNaCl (S25). In Experiment (I), the smallest CH4 emission was observed in S90. Methane emission in S30 was not significantly different with the non-saline control. The addition of gypsum showed significant lower CH4 emission in saline and non-saline treatments compared with non-saline control. In Experiment (II), the CH4 emissions in the saline treatments were not significantly different to the non-saline treatments except S25-G5. However, our work has shown that gypsum can lower CH4 emissions under saline and non-saline conditions. Thus, gypsum can be used as a CH4 mitigation option in non-saline as well as in saline conditions.

Spatiotemporal rainfall variability and low soil fertility are the primary crop production challenges facing poor farmers in semi-arid environments. However, there are few solutions for addressing these challenges. The literature provides several crop upgrading strategies (UPS) for improving crop yields, and biophysical models are used to simulate these strategies. However, the suitability of UPS is limited by systemization of their areas of application and the need to cope with the challenges faced by poor farmers. In this study, we reviewed 187 papers from peer-reviewed journals, conferences and reports that discuss UPS suitable for cereals and biophysical models used to assist in the selection of UPS in semi-arid areas. We found that four UPS were the most suitable, namely tied ridges, microdose fertilization, varying sowing dates, and field scattering. The DSSAT, APSIM and AquaCrop models adequately simulate these UPS. This work provides a systemization of crop UPS and models in semi-arid areas that can be applied by scientists and planners.