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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]

The aim of the study was to investigate the impact of phosphorus (P) dose application effects on bread wheat (Triticum aestivum) yield, mineral nutrients concentration and soil C (C) and nitrogen (N) concentration. From 1998to date, the same soil plots (200 m2) have been fertilized regularly with the same P fertilizer doses, namely 0 (PO), 50 (P50), 100 (P100), 200 (P200) kg P2O5 ha−1 as triple superphosphate (TSP). For the current study, fertilization was done 1 week before seed planting in 2013. Wheat yield increased with increasing P dose applications under long-term field conditions. Compared to the control treatment, 50, 100 and 200 P2O5 ha−1 application significantly increased wheat yield by 60%, 85% and 138%, respectively. Agronomic efficiency decreased with P-level increases. Indigenous root infection results and number of spore count decreased due to increasing P fertilizer application. With increasing fertilizer doses, soil organic C and N increased as well. It was concluded that since plants grow better with high P doses application, it may have a positive impact on organic matter (OM) remaining in the soil and increased soil C and N concentration. [ABSTRACT FROM AUTHOR]

Long-term agricultural research with annual and perennial cropping systems provides significant insight into the carbon sequestration potential of agriculture in the East Mediterranean region of Anatolia. This study explored the effect of different application rates of phosphorus (P) fertilizer on the storage and quality of soil organic carbon (SOC) and soil CO2 flux to assess the relationship between SOC and P application. The study was based on the hypothesis that long-term P fertilization can affect carbon sequestration in soil and impact soil CO2 flux. The objectives of the present study were to: (i) analyze the effect of long-term inorganic chemical P fertilization on SOC content and (ii) estimate the effect of long-term P fertilization on CO2 flux. Under crop rotation, corn (Zea mays L.) and wheat (Triticum aestivum L.) (CW system) were exposed to four fertilizer doses (0, 50, 100, and 200 kg ha−1), which were repeated annually over 20 years. During plant growth, bare soil and treated soil CO2 fluxes were determined several times. The results demonstrated that P fertilizer did not have a direct impact on the SOC of the summer-maize growing season and had a positive impact on SOC during the winter-wheat growing season. P fertilization levels have positive impact on atmospheric CO2 capture and increased SOC content. [ABSTRACT FROM AUTHOR]

The performance of DNDC (DeNitrification-DeComposition) and RothC (Rothamsted Carbon model) in simulating soil organic carbon (SOC) storage in soils under rice (Oryza sativa L.) – wheat (Triticum aestivum L.), maize (Zea mays L.) – wheat and cotton (Gossypium hirsutum L.) – wheat cropping systems was evaluated on field and regional scale. Field experiments consisted of N, NP, NK, PK, NPK, FYM, N + FYM, NPK + FYM, and control (UF) treatments. DNDC and RothC over-estimated SOC storage by 0.35–1.16 Mg C ha−1 (6–21%) in surface layer with manure application, compared with inorganic fertilizer treatments by 1.01–1.16 Mg C ha−1 (14–18%). Although RothC only slightly over-estimated SOC stocks, DNDC provided a better match for measured versus simulated SOC stocks (R2 = 0.783*, DNDC; 0.669*, RothC, p <.05). Model validation on independent datasets from long-term studies on rice–wheat (R2 = 0.935**, DNDC; R2 = 0.920**, RothC, p <.01) and maize–wheat (R2 = 0.895** for DNDC and R2 = 0.967** for RothC, p <.01) systems showed excellent agreement between measured and simulated SOC stocks. On a regional scale, change in SOC storage under Scenario 1 (NPK) was significant up to 8 years of simulation, with no change thereafter. In Scenario 2 (NPK + FYM), DNDC simulated SOC storage after 10 years was 2.0, 0.4, and 1.4 Mg C ha−1 in three systems, respectively. Amount of C sequestered in silt + clay fraction varied between 0.31 and 0.97 kg C 10 years−1 (Mg silt + clay)−1 under Scenario 1, and between 0.78 and 2.67 kg C 10 years−1 (Mg silt + clay)−1 under Scenario 2. [ABSTRACT FROM AUTHOR]

Carbon (C) mineralization of crop residues is an important process occurring in soil which is helpful in predicting CO2 emission to the atmosphere and nutrient availability to plants. A laboratory experiment was conducted in which C mineralization of residues of rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays), mungbean (Vigna radiata) and their mixtures was applied to the soil surface or incorporated into an Alfisols from Northwest India. C mineralization was significantly affected by residue placement and type and their interactions. Rice residue had a higher decomposition rate (k = 0.121 and 0.076 day−1) than wheat (0.073 and 0.042 day−1) and maize residues (0.041 day−1) irrespective of placements. Higher decomposition rates of rice and wheat were observed when placed on soil surface than incorporated in the soils. Additive effects of the contribution of each residue type to C mineralization of the residue mixture were observed. When mungbean residue was added to the rice/wheat or maize/wheat mixture, decomposition of the residue mixture was enhanced. Crop residues with low N and high C/N ratio such as maize, wheat, rice and their mixtures can be applied on the soil surface for faster C and N mineralization, thereby helping to manage high volumes of residues under conservation agriculture-based practices in northwest India. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the changes in soil organic carbon (SOC) stock in relation to the carbon (C) input from nine wheat-based cropping systems and untilled grass. The SOC pool ranged from 32.1 to 49.4 Mg ha−1at 0–20 cm and from 94 to 171 Mg ha−1at 0–100 cm for the arable soil, while in untilled grassland, it was higher (54 and 185 Mg C ha−1, respectively). SOC stock was observed to be lower at the unfertilized 2-year rotation and higher at the 4-year rotation with manure and mineral fertilization. The study showed a winter wheat yield decrease of 176.8 kg ha−1for a 1- Mg ha−1SOC stock change in the 0–20-cm soil depth. The estimated C input for SOC stock maintenance was from 266 to 340 g C m−2 year−1for winter wheat and rotations, respectively. Additional C input did not increase the SOC pool, suggesting that arable plots had a limited ability to increase SOC. These results provide guidance for the selection of management practices to improve C sequestration. [ABSTRACT FROM PUBLISHER]

The effect of conventional ploughing, mulching, and direct drilling on the soil organic C (soil Corg) contents through the soil profile and on total soil Corgstocks (0–45 cm) was investigated at five different German sites. All sites showed similar results: after 10–13 years, soil Corgcontents in the surface soil (0–10 cm) were 15–71% and 33–42% higher under direct drilling and mulching, respectively, than under ploughing (8–18 g kg−1). Under ploughing, the soil Corgcontents were distributed homogenously through the soil profile. Either mulching or direct drilling resulted in 3–28% higher soil Corgstocks than ploughing (49–116 t ha−1). However, the tillage management was no significant factor since the sites showed the effects to different extents but were the mathematical replications. Five to six years later, trends and values were similar. We concluded that the main effect of mulching or direct drilling was the stratification with higher soil Corgcontents in the surface soil. Since this is a positive means for soil protection, we suggested that the use of mulching or direct drilling can contribute to a sustainable soil management in crop rotations with sugar beet which are characterized by a strong physical impact on the soil during harvest. [ABSTRACT FROM PUBLISHER]

A field study was conducted during 2009–2012 on a soil that had been under organic farming practice since 2003. The treatment comprised three nutrient regimes, i.e., organic farming (OF), integrated nutrient management (INM), and recommended dose of chemical fertilizers (CF) under rice-based (Oryza sativaL.) cropping system with wheat (Triticum aestivumL) and vegetable crops for three consecutive years. The experiment was conducted using a split-plot design with three replications. The effect of fertilization practices and crop rotation was evaluated on changes in soil organic matter, soil organic carbon, and its different fractions as well as on crop yield. The highest total organic carbon (CT), oxidizable carbon (Cox), microbial biomass carbon (CMB), and labile carbon (CL) content after three years of crop cultivation were 27.26 mg g−1, 13.00 mg g−1, 0.72 mg g−1, and 7.48 mg g−1, respectively, in soil receiving no chemical fertilization. The percent microbial biomass carbon in total soil organic carbon varied from 1.88–2.20 under CF, from 2.09–2.18 under INM, and from 2.5–2.57 under OF. Organically fertilized soil had much higher carbon management index (147–161) compared with chemically fertilized soil (63–82). INM-based fertilization increased the yield of wheat, broccoli (Brassica oleracea Botrytis cymosa), and cabbage (Brassica oleraceavar.capitata), by 10.2%, 4.9%, and 3.8%, respectively, compared with chemically fertilized soil. However, organic fertilization improved the yield of rice and carrot (Daucus carota) by 8.3% and 4.5%, respectively. INM practice was more economical than organic practices but the latter was more beneficial when produce was sold at a premium price. [ABSTRACT FROM PUBLISHER]

Fertile soils are a fundamental asset for a sustainable rice–wheat cropping systems followed in 13 Mha in the Indo-Gangetic plains (IGP). Managing practices for the rice–wheat cropping system are changing and in turn influencing soil fertility parameters. In long-term rice–wheat cropping, soil organic carbon content declined only in soils having high initial organic carbon content. Otherwise, soil organic carbon content tends to remain unchanged or increase with continuous cropping and fertilizer/manure applications. Available P content of the soil also increased with P additions through fertilizers or manures. Soil quality deterioration with respect to K supplying power is being largely overlooked. Deficiency of zinc is widespread in the IGP, but with the extensive use of zinc sulfate, it has reduced in some areas. Deficiency of Fe, Mn, and B is also increasing. The western transects of the IGP are more productive not only because radiation decreases and minimum temperature increases from eastern to western IGP but also due to the application of large amounts of fertilizers and availability of assured irrigation in western transects. Since more nutrients are being removed than added through fertilizers, farmers have to apply increasing doses of fertilizers to sustain the productivity levels. [ABSTRACT FROM AUTHOR]

The status of available macronutrients [phosphorus (P) and potassium (K)] and soil organic carbon (SOC) of the surface soil under a rice–wheat cropping system was studied in 40 districts of the Indo-Gangetic Plains (IGP) of India. The soil samples were collected from the farmers' fields in four transects (Trans-, Upper, Middle, and Lower Gangetic Plains) of the IGP. The selection of farmers, villages, blocks, and districts within an agro-climatic zone (ACZ) was done on the basis of a multistage statistical approach. The available macronutrients were characterized as low, medium, and high. In Trans-Gangetic Plains, SOC, available P, and available K were in the ranges of 0.06–0.86%, 6.7–85.1 kg ha−1, and 50–347 kg ha−1, respectively. In Upper Gangetic Plains, the respective values were in the ranges of 0.05–2.55%, 4.5–155.0 kg ha−1, and 45 to 560 kg ha−1. Similarly, in Middle Gangetic Plains, these values were in the ranges of 0.04–2.01%, 4.7–183.7 kg ha−1, and 72–554 kg ha−1, respectively. In Lower Gangetic Plains, respective values were 0.12–1.78%, 2.2–112.0 kg ha−1, and 83–553 kg ha−1. In Trans-Gangetic plains, the majority of the soils in the midplains ACZ representing intensively cultivated rice–wheat system area were low to medium in SOC and available P, whereas available K status was medium to high. Irrespective of the agroclimatic variations, more than 90% of the soils were low to medium in SOC and available P with a marginal deficiency of K. The majority of the coarse-textured soils in Shiwaliks were found to have low to medium SOC and available P, whereas less intensively cultivated arid zone soils were high in SOC, available P, and available K. In Upper and Middle Gangetic Plains, the majority of the soils tested medium for SOC and medium to high in available P and K. The dominance of medium status of available P in these soils could be due to mining of soil P by the rice–wheat cropping system practiced in these regions for more than 300 years. In Lower Gangetic Plains, the SOC was medium to high in most of the soils, whereas available P and K were high. Recent introduction of the rice–wheat system on intensive scale in these traditionally rice-growing areas resulted in less mining of SOC, P, and K. [ABSTRACT FROM PUBLISHER]

Application of an optimum rate of nitrogen is very crucial to maintain the sustainability of a rice-wheat cropping system (RWS). A three-year field experiment was conducted on acid sandy loam soil to select the best N-management practice, along with tillage and crop residue (CR) incorporation for RWS. Changes in soil properties were assessed to determine the effect of tillage and crop residue application on soil fertility, loss and uptake of N, and yield of rice and wheat (RW) crops. Application of CR and intensive tillage increased the N leaching loss; however, it also increased N uptake and yield of RW crops and resulted in minimal degradation of soil environment. Overall results of loss, uptake, N-use efficiency, and yield attributes of RW crops indicated that a comparatively lower rate of N along with RW residue incorporation in combination with less intensive puddling for rice and medium-intensive tillage for wheat can be opted as sustainable management practices. Thus, the use of comparatively lower rate of N will reduce water pollution from extra leached N and reduce the cost of farming, too. On the other hand, use of RW residue will enrich the soil organic carbon pool and improve the quality of the soil. Use of less intensive tillage along with RW residue application will increase the porosity of the soil, reduce soil erosion, and help sustain the RW system. [ABSTRACT FROM AUTHOR]