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Soil acidification is a natural phenomenon that human activity can accelerate or manage. Acid soils limit plant growth by reducing nutrient availability and causing aluminum toxicity, significantly reducing crop production. Liming has proven efficient for increasing crop yield on acidic soils. Knowledge is required on the effect of liming on the soil pH dynamics to find the suitable material, application rate, timing, and method. The objective of this study was to develop a prediction model of soil pH temporal variations after lime application using data from the literature. A database was built from research results extracted from 16 scientific papers that provided data on soil acidity changes over time under different liming treatments. Machine learning (ML) was used to predict soil pH dynamics from eight predictive parameters: rate of application, time since application, neutralizing value (CCE), grind fineness (D50), pH measurement depth, soil acidity (pH prior to liming), the type of solution used for pH measurement (water or CaCl 2) and the soil:solution ratio used to measure pH. Since soil pH fluctuates with seasons, all pH values were expressed as difference between the actual pH value and that of an unlimed control (ΔpH). The Random Forest (RF) algorithm was tested to predict ΔpH over time. On testing, we obtained an R2 between measured and predicted ΔpH values of 0.881 and an RMSE of 0.230. These results are excellent, considering the heterogeneity in soils, liming materials, and pedoclimatic conditions found in the 16 papers. The primary factors influencing ΔpH, ranked by their impact are application rate, time elapsed post-application, and lime characteristics including its grind fineness and neutralizing value. • Random Forest robustly predicts soil pH change over time following lime application. • The predictors are: rate, neutralizing value, particle size, depth, and initial pH. • The model predicts that, on average, lime increases soil pH for 82 weeks. • Machine learning models are promising tools in managing liming practices. [ABSTRACT FROM AUTHOR]

Liming materials are widely applied to alleviate soil acidification and increase rice yield in acidic soils, but their effects on nitrogen (N) use efficiency are still unclear. Here, we conducted a field-, pot-, and micro-plot experiment to investigate how the application of slaked lime (i.e., Ca(OH) 2) affects the fate of chemical fertilizer-N and straw-N in a double rice cropping system. In the field experiment, liming increased grain yield and N uptake by an average of 9.0% and 10.6%, respectively. In contrast, CaCl 2 application did not affect rice yield and N uptake, suggesting that the effects of lime application were not related to the addition of Ca2+. Results from a 15N tracer experiment (i.e., 15N-labeled urea and straw) indicated that liming reduced N uptake from fertilizer (−5.7%), but increased N uptake from straw (+31.3%). Liming also reduced soil retention of both urea- and straw-N and increased their loss rates. Taken together, our results indicate that although liming increases rice yield and N uptake, it lowers the use efficiency of fertilizer N and facilitates N losses. In addition, our results emphasize the need for long-term studies on the impact of liming on soil N dynamics in paddy soils. • Liming of an acidic rice paddy soil increased both rice yield and N uptake. • Addition of Ca2+ did not affect rice yield and N uptake. • Liming reduced N uptake from fertilizer but increased that from straw. • Liming reduced soil retention of both urea- and straw-N and increased their loss rates. [ABSTRACT FROM AUTHOR]

• Surface liming reduced soil acidity down to −60 cm one year after its application. • Liming increased soybean grain yield by 9%, but it had no effect on cereal crops. • The lime reactivity had no effect on crop grain yield. • Gypsum did not increase crop grain yield in this moderate acidic Oxisol. • Combined application of gypsum and lime did not benefit crop yields. The low solubility of lime (CaCO 3) and the absence of soil disturbance in fields under no-tillage (NT) may diminish the effectiveness of surface liming to reduce exchangeable Al3+ (toxic to plants) and increase the base saturation in deep soil layers. However, the effects of subsurface soil acidity can be attenuated by applying agricultural gypsum (CaSO 4 ⋅2H 2 O), which is more soluble than lime, and thus, can leached bases (exchangeable Ca2+, Mg2+ and K+) and S-SO 4 2− to deeper soil layers as well as decrease Al3+ toxicity to plants. Therefore, gypsum can be applied individually or in combination with lime. Herein, we conducted a field experiment aiming to evaluate short- (1 year) and long-term (11 years) effects of surface liming and gypsum application on the chemical properties of the 0.00–0.10, 0.10–0.20, 0.20–0.40 and 0.40–0.60 m soil layers and also on crop yield of 22 crop seasons (i.e., 10 soybean, 3 maize, 4 white oat, 3 wheat and 2 barley crops). The study was performed in a clayey Typic Hapludox of moderate acidity managed under NT for more than 25 years in Guarapuava, Paraná State, southern Brazil. Three soil surface-applied lime strategies were tested in order to raise base saturation to 70%, namely: (a) 4.62 Mg ha–1 rate of lime of low effective calcium carbonate equivalent (ECCE = 75%); (b) 3.47 Mg ha–1 rate of lime with a high ECCE value (101%); and (c) the same rate of high-ECCE lime split in three applications (i.e., 1/3 at the start of experiment; 1/3 after 1 year and 1/3 after 2 years). A control treatment without liming was also conducted. The liming strategies were combined with four rates of agricultural gypsum (i.e., 0, 3, 6 and 9 Mg ha–1) applied at the start of the experiment. Our findings did not reveal synergistic effect of lime and gypsum on soil chemical properties nor on crop yield. Gypsum resulted in very slight gains in grain yield (4% on average) and limited to just 25% of cereal (corn and winter cereals) crop seasons. On the other hand, liming increased soybean yields by 14% in 40% of crop seasons. Gypsum was more efficient than lime in raising exchangeable Ca2+ levels up to −0.60 m in the short term; however, lime promoted greater reduction of soil acidity and had a more marked residual effect on exchangeable Ca2+ contents than gypsum. The liming strategies did no promote substantial differences in crop yield, but low-ECCE lime sustained better soil chemical condition to plant growth for a longer period. Surface liming efficiently reduced subsurface acidity in a moderately acidic Oxisol managed under NT even in the short-term, promoting increments on soybean crop yields. In this case, the application of gypsum rates did not bring additional benefits to soil or plant yield. [ABSTRACT FROM AUTHOR]

• Liming has been recognized to be beneficial for soil physical properties. • The physical resilience of a soil is related to its structural stability. • It may take several years to develop a sustainable structure system. Liming is a well-established practice to ameliorate acidic soils worldwide. However, the role of liming in soil structure formation and its relation to the nitrogen cycling is only little explored. We hypothesized that improved physical and mechanical soil properties, which are directly linked to soil structure, lead to lower nitrogen losses in an agricultural system. Water holding capacity, total pore volume, bulk density, hydraulic conductivity, shear stress and pre-compression stress were quantified in the topsoil of three surveys located in Germany on different soil types: Eutric Gleyic Cambisol (Loamic) (Magdeburg, Saxony-Anhalt), Haplic Luvisol (Neubrandenburg, Mecklenburg-Western Pomerania) and Eutric Cambisol (Loamic) (Puch, Bavaria). The field experiments were arranged in a Randomized Complete Block Design and treated with two different rates of lime (calcium carbonate). Furthermore, three rates of nitrogen in form of urea or calcium ammonium nitrate were applied every year. Liming significantly increased the pH, plant available water capacity, total pore volume and decreased bulk density in the soils six months after application, but twelve months after lime application the soil structure collapsed again causes by ploughing and chiseling. We, therefore, assume a positive influence of lime application on soil physical parameters, if tillage is excluded at least initially. On the other hand, our results from the shear stress parameters and the pre-compression stress values indicate that their changes need time and we assume that it may take several years to develop a sustainable structure system. [ABSTRACT FROM AUTHOR]

Crop yield gains and improvements in surface and subsurface soil chemical properties are evident when agricultural lime and gypsum are used in high-acidity soils. However, there is scarce information on the effects of lime and gypsum application on no-till tropical soils previously treated with these additives (low-acidity soils). The duration of the effects of lime applied to the soil surface varies according to lime rate, product characteristics, soil conditions, and water and thermal regimes. Such residual effects influence the timing of lime reapplication. This study aimed to investigate the effects of surface application of agricultural lime and gypsum on soil chemical properties, soybean and second-crop corn yields, and lime residual contents. The experiment was conducted on a Red Latosol with a very clayey texture in Floresta, Paraná, Brazil. Four rates of dolomitic lime (0.0, 2.6, 5.4, and 8.1 Mg ha−1) and agricultural gypsum (0, 4, 8, and 12 Mg ha−1) were used. The experimental design was a randomized complete block with subplots and four replications. The experiment lasted for four soybean seasons and three second-crop corn seasons. At 6, 12, 24, and 36 months after treatment, soil samples were collected from the 0.00–0.05, 0.05–0.10, 0.10–0.20, 0.20–0.30, 0.30–0.40, and 0.40–0.60 m layers for chemical analysis. No significant interaction effects were observed on soil chemical properties. Liming resulted in soil alkalization, with a consequent reduction in Al3+ and an increase in Ca, Mg, base saturation, and pH. Residual lime was not detected in layers deeper than 0.05 m, suggesting a lack of physical movement of particles in the soil pore space. Residual lime was detected on surface soil (0.00–0.05 m) up to 36 months after application, demonstrating the low reactivity of lime on no-till soils. At 6 months after gypsum application, there was an increase in Ca2+ levels up to the 0.6 m layer, whereas Mg2+ levels were reduced throughout the soil profile for up to 36 months. In no-till soybean–second-crop corn rotation systems, use of agricultural gypsum alone did not provide consistent effects on crop yield and reduced foliar Mg contents. Under the studied conditions of low acidity, liming did not produce significant differences in crop yield but improved soil chemical properties for plant growth under no-till. • Residual lime was restricted to the 0.05 m layer. • Lime remained on the soil surface for up to 36 months after application. • Agricultural gypsum increased calcium content up to 0.6 m depth for 6 months. • Lime and gypsum application increased corn yield in some seasons. • Soybean yield did not improve with lime and reduced with gypsum in the first season. [ABSTRACT FROM AUTHOR]

The rate and method of lime application modify soil chemical attributes, but the re-acidification process after liming remains poorly understood in the long-term. This study aimed to assess the long-term effect of surface and incorporated liming on shifting soil use from native grassland of South Brazilian Campos to no-tillage system (NTS) for grain production in a highly acidic sandy-loam Ultisol. In 1994, an experiment in a randomized block with split plot design and four replications was installed in Southern Brazil. The main plot consisted of lime application method (surface or incorporation by soil tillage), while the subplots were lime rates (0.0, 2.0, 8.5 and 17.0 Mg ha −1 ), corresponding, approximately, to 0, 1/8, 1/2, and 1 fold the recommended dose to rise soil pH to 6.0 in the 0–20 cm soil layer. The 2 Mg ha ‒1 treatment had reapplication every two years until soil accumulated 8 Mg ha ‒1 of lime. In October 2006 and 2012 (i.e., 12 and 18 years after lime application), soil samples were collected at every centimeter from 1 to 10 cm depth, every 2.5 cm from 10 to 25 cm, every 5 cm from 25 to 50 cm and 50 to 60 cm. The chemical attributes related to soil acidity were evaluated. Even after 18 years of lime application, the re-acidification process recovered only 50% of the exchangeable Al and 30% of the potential acidity compared to native soil. Lime incorporation before NTS adoption proved to be more rapid and efficient to mitigate soil acidity than surface liming, and it is suitable for correction of deep-layered soil acidity in the soil profile. Surface lime application induced a lower alkalinization front in the soil profile, and even after 18 years there was no neutralization of total exchangeable Al in the 10–20 cm layer. [ABSTRACT FROM AUTHOR]

Liming with 'structure lime', comprising approximately 80–85% ground limestone and 15–20% slaked lime, has been promoted in subsidised environmental schemes in Sweden since 2010 to increase clay aggregate stability and mitigate particulate phosphorus losses to surface waters. To date, approximately 65,000 ha have been structure-limed. Apart from stabilising aggregates, liming may also improve other physical properties, such as soil strength. This study examined the effect of increasing application rate (0–16 t ha-1) of structure lime on soil strength, approximated by horizontal (draught requirement) and vertical (penetrometer resistance) measurements, in eight field soils (clay content 26–38%) to which structure lime had been applied two, three, four or six years previously. Draught requirement when cultivating with a multipurpose cultivator significantly decreased (by 11%) with the highest application rate of structure lime (16 t ha-1) compared with an unlimed control. This reduced the wheel power requirement by 7.1 kW and diesel consumption by 1.2–1.4 L ha-1, and lowered CO 2 emissions by 3–4 kg ha-1. To clarify the general effect of structure liming, the mean value of all limed treatments was compared with that of the unlimed control. This showed that structure liming in general significantly reduced the draught requirement (by 7%). However, penetrometer resistance measurements revealed no significant effects of structure liming and no relation between draught requirement and penetrometer resistance measurements. Overall, the results indicate that structure liming can reduce fuel consumption, due to easier soil tillage, and thus lower CO 2 emissions. • Cultivator draught requirement was measured in structure limed field trials. • A towing eye with sensors that can measure forces in three directions was used. • Structure liming reduced horizontal draught requirement by 7%. • Reductions corresponded to decreases of 1.2–1.4 L diesel ha-1 and 3–4 kg CO 2 ha-1. • Structure liming did not affect penetrometer resistance in this study. [ABSTRACT FROM AUTHOR]

A significant area in Brazil is covered with degraded pasturelands, which could be more appropriately used under no-till system. These soils are highly acid and physically fragile, and then there is a need to identify a better liming strategy that will improve the establishment of no-till systems. We hypothesized that the surface application of lime would be more efficient to alleviate soil acidity on degraded pastureland soils. A 4-year field trial examined the effect of a lime application (4.8 Mg ha −1 ) that had either been incorporated (0–20 cm) or surface-applied to an acid sandy loam Oxisol, originally under degraded pasture in Southern Brazil. Control treatments (no-lime) were applied with and without soil disturbance. A black oat ( Avena strigosa Schreb) – soybean ( Glycine max L. Merrill) cropping sequence was used for 4 years after no-till establishment. Soil chemical attributes, plant nutrient uptake, black oat dry biomass production and soybean grain yield were assessed. Soil acidity amelioration was achieved either by incorporating the lime or applying it onto the soil surface. Lime incorporation resulted in a faster neutralization reaction, whereas surface-applied lime provided longer lasting soil profile benefits. At 0–5 cm layer, both tillage treatments, especially with lime application, provided lower soil organic carbon levels than no-till treatments, with or without lime application, until the second year. These differences in soil organic carbon levels were not observed at the end of evaluation, after 4 years, probably because the residual tillage effect disappeared. Over time, the soil organic carbon levels at 5–10 cm layer were slightly increased or maintained close to the initial level, regardless of treatment. Overall, the plants responded to lime application, with an increase by 35% on soybean yield, regardless of the application method. Surface liming provided better economic returns than incorporated liming. Lime incorporation is not recommended in degraded lands due to the risks of SOC losses with soil disturbance and rapid pH increase. Despite of high soil acidity before no-till cultivation, the surface application of lime was the best alternative for alleviating soil acidity when establishing a no-till system on degraded pastureland. [ABSTRACT FROM AUTHOR]

The selection of an appropriate soil tillage system for improving yields and longevity is an important decision in sugarcane cultivation. In the present study, the effects of different soil tillage systems and methods of applying lime on sugarcane stalk and sugar yield performance as well as soil fertility parameters were evaluated throughout the sugarcane crop cycle. The experiments were established in two locations in April 2015 and conducted until August 2019, corresponding to a total of 4 growing seasons. A field study with a randomized block design was established with four replicates considering 4 treatments: conventional soil tillage system (CT), deep strip-tillage system (DT) and modified deep strip-tillage system (MDT), all with the same lime rate; and a standard treatment (control, CT without liming). Immediately after harvesting plant cane (18 months (mo) after planting), first ratoon (30 mo after planting), second ratoon (42 mo after planting) and third ratoon (54 mo after planting), soil samples were collected from a depth of 0.0–1.00 m, stratified every 0.2 m. Leaf material was sampled during the period of full vegetative growth. Analyses of soil chemical fertility, leaf concentrations of elements, and sugarcane yield components were performed. MDT was found to correct soil acidity most efficiently, mainly due to the positioning of the lime application. Under high aluminum saturation (AS), especially in deeper layers, deep lime placement was more effective and resulted in the best distributions of calcium (Ca2+) and magnesium (Mg2+), the highest base saturation (BS) and the lowest AS compared with the other treatments. Lime application was more important than the tillage system for improving the sucrose concertation and total recoverable sugar (TRS), whereas the tillage system affected the stalk yield and, consequently, the yield of sugar. Compared with DT and CT, the average stalk yield was 4.1% and 9.4% higher, respectively, under MDT at Macatuba and 6.3% and 15.3%, higher, respectively, under MDT at Piraju. Similarly, MDT improved average sugar yield by 3.7% and 10.4% at Macatuba and 6.1% and 16.3% at Piraju. Overall, long-term assessments, which are important for semi-perennial crops like sugarcane, showed that the both deep strip-tillage were most effective. • Strip-tillage system is an innovative soil tillage for sugarcane plantation. • Deep liming placement is important to reach longevity for sugarcane ratoons in highly weathered clayey soils. • Soil fertility is enhanced by deep liming placement. • Sugar and stalk yield is affected by the relation of lime application and tillage systems. [ABSTRACT FROM AUTHOR]

Lime slotting is a strategy for the amelioration of acidic soil profiles, whereby vertical seams of lime-amended soil traverse the acidic horizon. Two experiments characterized the above-ground and below-ground response of wheat to the lime amendment of 4 cm or 8 cm wide slots traversing the 7–40 cm deep acidic (pH = 3.9), Al-toxic subsoil horizon in an 80 cm deep constructed acidic soil profile. The growth of wheat rows responded to the proximity, but not the width of the limed slots. Wheat rows positioned above or adjacent (0–4 cm) to limed slots had greater shoot growth than those in the non-amended soil profile, whereas rows positioned 4 cm or more away from a limed slot were not significantly different (at α = 0.05) to those in the non-amended profile, regardless of the width of the 4 cm or 8 cm wide limed slots. Growth responses to the limed slots were realized at the early stages of plant growth and sustained until anthesis: rows positioned above the limed slots had 83% more tillers at 28 days after sowing, 58% greater green canopy area 35 days after sowing and 13% more spikelets per ear at anthesis compared to those in the non-amended profile. A rubidium tracer within the limed slots revealed that the proximity of wheat rows to the limed slots strongly influenced the timing at which the wheat roots exploited them. Wheat rows positioned above or adjacent (0–4 cm) to a limed slot accumulated the rubidium tracer within 21 days after sowing, whereas wheat rows positioned 4, 9 or 11 cm away from the limed slot did not access it until 35, 42 or 49 days after sowing, respectively. The uptake of a rubidium tracer from acidic or lime amended soil sections was strongly correlated with the length of roots within the respective soil sections. The limed slots traversing the acidic subsoil horizon functioned in two ways. Firstly, as discrete sanctuaries for root proliferation within the acidic layer, root length density was 3–7-fold greater than in non-amended soil sections, primarily due to the proliferation of fine (≤ 2 mm diameter) roots that were inhibited in the acidic soil sections. Greater root proliferation within the limed slots enabled greater uptake of nutrients and, to a lesser extent, water from the 7–40 cm deep acidic subsoil horizon. Secondly, the limed slots acted as conduits for roots to traverse the acidic, Al-toxic horizon. Uptake of water and a strontium tracer from the 40–80 cm deep subsoil horizon (beneath the 7–40 cm deep acidic layer) demonstrated that the limed slots enabled plant rows positioned above them to acquire water and nutrients from the 40–80 cm deep horizon 1–2 weeks earlier and in greater quantities than in the non-amended profile. However, for plant rows positioned 4 cm or more away from the limed slots, root activity in the 40–80 cm deep horizon was not significantly different (at α = 0.05) to those in the non-amended profile. Therefore, responses to lime slotting amendments are likely to be greatest where limed slots are positioned beneath wheat rows, and least where they are positioned in the interrow. • Lime slotting in an acidic soil profile increased wheat growth. • Wheat growth responded to the proximity, but not the width of limed slots. • Proximity to a limed slot influenced the timing at which roots intercepted it. [ABSTRACT FROM AUTHOR]

Highlights: [•] Combining no-tillage with a Ca-amendment was the best practice in acid degraded soils. [•] In some cases tillage suppressed the positive effects of liming. [•] Carbon and glomalin-related soil proteins seem to play a role in the alleviation of Al toxicity. [Copyright &y& Elsevier]

Highlights: [•] Soil acidity attributes were more favorable to crops growth up to 10cm under NT. [•] Liming was not efficient in neutralizing the Al toxicity below 10cm depth under NT. [•] Effects of soil management systems were predominant on the soil acidity attributes. [•] Oat and lupine were more efficient in P cycling increasing the soil available P. [•] Fallow in the winter period resulted in lower P and K availability in the soil. [Copyright &y& Elsevier]

• Interactions between sward management and liming reduced soil organic carbon. • Nitrogen increased and C:N ratio decreased under liming and hay cutting. • Changes to soil organic matter dynamics did not affect soil carbon stocks. • Upland grasslands can be managed using known methods without reducing soil carbon. • Regular organic matter input by livestock can help maintain soil carbon stocks. Soils in less favoured areas, (LFA's) defined as areas where unfavourable environmental conditions allow only extensive farming systems such as livestock rearing, are relatively stable, being rarely ploughed or disturbed, and cover extensive upland regions of the UK and Europe. Under low intensity management these soils have the potential to act as long-term carbon stores, mitigating the effects of climate change and potentially acting as a source of income for rural economies. However, upland grasslands are sensitive to management decisions, and careful planning is needed to ensure that they continue to provide a range of ecosystem services. Using the long-term grassland experimental plots at Brignant, Wales, management and liming effects on soil organic carbon and related soil parameters under long-term permanent pastures were explored. Results showed that interactions between management and liming could significantly influence carbon storage potential, making a difference of up to 0.45 kg C m−2 in Hay-cut swards. The greatest reductions were found under pastures that had been cut (rather than grazed) and limed, probably due to a combination of enhanced soil microbial activity, increased root production and a lack of fresh biomass. These results indicate that while the potential to further increase soil organic carbon may be limited, grazing for all or part of the year can reduce losses by providing regular organic matter inputs. [ABSTRACT FROM AUTHOR]

Abstract: Brazil has extensive pasturelands that could be used, in part, for grain production. A no-till system was established on pastureland to obtain a suitable method for liming upon conversion from pasture to a no-till cropping system. The study was conducted during the period from 1998 to 2003, in Paraná State (Brazil), on a clayey, kaolinitic, thermic Rhodic Hapludox. Soil chemical properties and grain production were evaluated after application of dolomitic lime. The experimental treatments were: control (no lime), split application of lime on the surface (three yearly applications of 1.5tha−1), surface lime (4.5tha−1), and incorporated lime (4.5tha−1). The lime rate was calculated to raise the base saturation in the topsoil (0–0.20m) to 70%. The cropping sequence was: soybean (Glycine max L. Merril), barley (Hordeum distichum L.), soybean, wheat (Triticum aestivum L.), soybean, corn (Zea mays L.), and soybean. When surface-applied, liming neutralized acidity and increased exchangeable Ca2+ +Mg2+ to a depth of 0.10m, and to a depth of 0.20m, when incorporated. Split application of lime on the surface resulted in a slower neutralization reaction only in the first year after liming. Soil pH increased with liming and resulted in a decline of exchangeable Al3+ and an increase in base saturation. At 0–0.05m depth, lime incorporation resulted in lower levels of soil organic matter than surface application. It took 4–5 years after lime incorporation for soil organic matter to return to its baseline value. Liming increased grain yield in only one crop of soybean, and only when lime was surface-applied at the full rate. However, cumulative grain yield was higher with liming than in the control treatment (no lime), regardless of the application method. Surface application of lime, at either full or split rates, was the best alternative to neutralize soil acidity when establishing a no-till system on pastureland because, in addition to conserving soil structure, it provided a greater economic return. [Copyright &y& Elsevier]

This study investigated the long-term effect of lime application and tillage systems (no-till, ridge-till and chisel plow) on the activities of arylamidase and amidohydrolases involved in N cycling in soils at four long-term research sites in Iowa, USA. The activities of the following enzymes were assayed: arylamidase, l-asparaginase, l-glutaminase, amidase, urease, and l-aspartase at their optimal pH values. The activities of the enzymes were significantly (P<0.001) and positively correlated with soil pH, with r values ranging from 0.42&ast; to 0.99&ast;&ast;&ast; for arylamidase, 0.81&ast;&ast;&ast; to 0.97&ast;&ast;&ast; for l-asparaginase, 0.62&ast;&ast;&ast; to 0.97&ast;&ast;&ast; for l-glutaminase, 0.61&ast;&ast;&ast; to 0.98&ast;&ast;&ast; for amidase, 0.66&ast;&ast; to 0.96&ast;&ast;&ast; for urease, and 0.80&ast;&ast;&ast; to 0.99&ast;&ast;&ast; for l-aspartase. The Δactivity/ΔpH values were calculated to assess the sensitivity of the enzymes to changes in soil pH. The order of the sensitivity of enzymes was as follows: l-glutaminase>l-asparaginase>amidase>arylamidase>urease>l-aspartase. The enzyme activities were greater in the samples of the 0–5 cm depth than those of the 0–15 cm samples under no-till treatment. Most of the enzyme activities were significantly (P<0.001) and positively correlated with microbial biomass C (Cmic) and N (Nmic). Lime application significantly affected the specific activities of the six enzymes studied. Results showed that soil management practices, including liming and type of tillage significantly affect soil biological and biochemical properties, which may lead to changes in nitrogen cycling, including N mineralization in soils. [Copyright &y& Elsevier]

• Liming increases the amount of biological nitrogen fixation. • Liming provides higher soybean yields and a more positive N-balance. • Soil pH and Al saturation are key factors in biological nitrogen fixation. Soil acidity can impair biological N 2 fixation (BNF) and increase soybean (Glycine max L.) reliance on soil N to satisfy its plant N demand. This study aimed to evaluate the effect of liming, fertilization strategy, and grazing on: i) the N supplied via BNF process, ii) partial N-balance, and iii) soybean yield, in an integrated crop-livestock system under a non-tilled sandy and acidic Acrisol. Initial soil conditions were soil pH of 4.0 and Al saturation of 50%. Limestone was applied to rise soil pH to 6.0 and a control area was kept with the initial soil conditions. Soybean was grown in the summer and Italian ryegrass (as a cover crop or grazed by sheep) in the winter. Fertilization strategies consisted in applying P and K prior to soybean or ryegrass. Partial N-balance was calculated by the difference between N derived from BNF and N removed in soybean seeds. Contribution of N from the atmosphere to soybeans was on average 62 and 66% in plots without and with liming, respectively. The fixed-N was 27% greater under low soil acidity due to lime. Partial N-balance was positive in both treatments, but 57% greater in the limed- relative to the non-limed (+58 kg ha−1) soils, resulting in 11% soybean yield increase when lime was added. The most relevant soil chemical properties influencing N fixation were soil pH and Al saturation. Grazing and fertilization strategies had no effect on soil acidity properties, N supply, and soybean evaluations. Further research should explore the long-term effect of grazing, fertilization strategies, and liming. [ABSTRACT FROM AUTHOR]

•Effect of no-tillage (NT) and liming on a rainfed oat-vetch mixture was evaluated. •Mycorrhizal root colonization of both crops was higher under NT and in limed plots. •Oat N content was increased by liming and NT while N vetch content only by liming. •Plant P contents were unaffected and the N:P ratio was increased by liming and NT. •Crop yields were increased by NT and liming showing a positive interaction. The combination of no-tillage (NT) and liming has been proposed as feasible means to restore degraded acid soils. However, the synergistic effect of both practices on nutrient acquisition by crops has not been addressed. Similarly, the simultaneous impact on arbuscular mycorrhizal fungi (AMF) is under-investigated despite its essential role in plant growth and nutrient uptake, especially under stress conditions. We evaluated the plant growth, nutrient acquisition and mycorrhizal root colonization at three stages during a growing season along with soil properties of a rainfed oat (Avena sativa L.) and vetch (Vicia sativa L.) mixture under Mediterranean condition. The experiment was located in south-west Spain where tillage type (no tillage: NT and traditional tillage: TT) and lime application were evaluated in a full factorial design. Liming raised soil pH, increased soil calcium and magnesium availability and stimulated the microbial activity while NT enhanced soil carbon content. Both practices improved oat biomass production (40 times at biomass harvest) and root colonization of both crops (80 % and 60 % higher respect to TT without liming in oat and vetch, respectively). Liming enhanced vetch biomass production (20 times at harvest) and foliar N content, while NT increased foliar N content of oat. Plant phosphorous (P) contents were unaffected by the treatments. The high N:P of both crops indicates P limitation despite of the high soil P content. The P limitation together with the increased N supply could lead to strengthening of mutualism between plants and AMF, where P acquisition through AMF is stimulated in order to take advantage of the "luxury" N supply provided by NT and liming. Thus, both practices together increase nutrient use efficiency by stimulating crop-microbe interactions. [ABSTRACT FROM AUTHOR]

• Manure application had no consistent effect on soil pH or lime buffer capacity. • Cropping system influenced pH more strongly than tillage or poultry litter. • Continuous cotton depleted soil fertility more than continuous corn or millet. Soil acidity is a constraint to global soil and food security, yet access to limestone to correct this problem is limited in many parts of the world. Research suggests that animal manures have a liming effect on acidified soils, representing a potential solution. This long-term (15 year) study used a split plot design to evaluate the effect of conventional tillage (CT) vs no-till (NT) (main plot) under conventional (CF) and poultry litter (PL) fertilizer source applications (sub-plots). A succession of three cropping systems consisting of cotton (Gossypium hirsutum L.) with a winter wheat (Triticum aestivum) cover crop, corn (Zea mays) with rye (Secale cereal), and millet (Panicum miliaceum) with rye was implemented. The soil is a Cecil sandy loam (1:1 kaolinitic). Changes in soil pH, soil organic carbon (SOC), and lime buffer capacity (LBC) were compared among the four treatments CTCF, CTPL, NTCF, and NTPL. The CTPL treatment had a 0.6 unit pH increase in the top 15 cm. However, cropping systems had more effect than tillage or fertilizer source on both soil pH and LBC. All treatments resulted in some increase in subsoil pH. Lime buffer capacity remained unchanged at all but the 76–91 cm depth, where all treatments exhibited a decrease ranging from 27 to 43 kg CaCO 3 eq ha−1 pH unit−1 year−1. Our results suggest that previously reported liming effect of animal manures should be examined in the context of soil type and cropping system to better understand the true mechanism(s) of soil acidity amelioration. [ABSTRACT FROM AUTHOR]

• Liming increased gross N mineralization and nitrification during the summer fallow. • No-tillage enhanced the liming effect on gross N mineralization. • N immobilization was higher in traditional tillage. • The gross N transformations and microbial indicators decreased during the summer period. • During the fallow period, NH 4 +, DOC and DON accumulated in all the treatments. In the Mediterranean rainfed agriculture, a summer fallow is necessary because of the severe drought and high temperatures. Due to suppressed plant nitrogen (N) uptake during this period, an accumulation of inorganic N in the soil may occur, which could be lost from the system during the first autumn rains. Both mineralization and nitrification rates can be affected by agricultural practices, such as tillage or liming, influencing the amount of available N present in the soil during the fallow period. In this study, we investigated the effects of two common agricultural practices, no-tillage (instead of traditional tillage) and liming, on soil gross N transformations during the summer fallow. Liming increased gross N mineralization (from 1.21 to 1.78 mg N kg−1 day−1) and gross nitrification (from 0.44 to 0.76 mg N kg−1 day−1) while traditional tillage increased N immobilization. Tillage did not affect gross nitrification but the effect of liming on gross N mineralization was enhanced in no-tillage plots. The total bacteria abundance was enhanced by liming and no-tillage and seemed to be responsible for gross N mineralization and immobilization. The gross mineralization, nitrification and microbial immobilization decreased during the summer fallow with an overall reduction by 40%, 56%, 74% and 54% in gross N mineralization, gross nitrification, ammonium immobilization and nitrate immobilization, respectively. The accumulation of ammonium could be interpreted as a consequence of the decoupling between ammonium production and consumption rates. The increase of gross N mineralization and nitrification caused by liming application could result in augmented risks of N losses via nitrate leaching and gaseous losses in autumn, especially under no-tillage. However further studies are required to elucidate the nitrate fate of the in Mediterranean agricultural soils under those management practices. [ABSTRACT FROM AUTHOR]