Soil Amendments for Sustainable Intensification

Maintaining proper soil health is one essential element of sustainable agriculture and safeguarding ecosystem services. Beyond rendering provisioning services like food, fiber and fuel supply, soils play a critical role in services like climate regulation, water quality and supply regulation through soil functions of regulation of greenhouse gas (GHGs) emissions, filtration/buffering of substances in water, water infiltration and water flow in soil, etc. (FAO and ITPS 2015). Supporting cultural services and soil functions like nutrient cycling, soil formation, medium for seed/root growth and natural and cultural landscape diversity also depends on the state of soil health..

Balanced nutrient management: Effects on plant zinc

Participatory on-farm research on the diagnosis and management of nutrient disorders over the last decade by the International Crops Research Institute for the Semi- Arid Tropics (ICRISAT) and its partners has established that multi-nutrient deficiency is the norm rather than an exception. The results of analysis of a large number of soil samples from farmers’ fields in the semi-arid tropical regions of India showed that generally the soils are low in organic carbon (C), indicating general poor soil health. Apart from deficiencies of the major nutrients nitrogen (N) and phosphorus (P), the deficiencies of secondary nutrient sulfur (S) and micronutrients especially zinc (Zn) and boron (B) are widespread and indeed revealing. The results from a large number of on-farm follow-up trials comparing soil test-based balanced nutrition with farmers’ inputs showed that balanced plant nutrient management significantly increases crop productivity (Sahrawat and Wani 2013) and enhances grain and straw quality of crops (Sahrawat et al. 2008). Currently..

Evaluation of distilling the entire digest or an aliquot for total nitrogen determination in soil digests

Accurate and easy to adapt methods of total soil N determination are a prerequisite for N balance research. For JSN balance studies certain modifications of the regular methods are generally adopted, e.g. the distillation of an aliquot of the digest in preference to the entire digest. However, comparative evaluation of such methods has not been investigated. In this study, three methods of distilling soil digests were evaluated for the determination of total N in diverse Alfisols and Vertisols. These are distillation of a clear aliquot (suspended materials allowed to settle) of the digest, distillation of an aliquot with suspended materials, following digestion in a block digestor, and distillation of the entire digest following macro-Kjeldahl digestion. The total N content of soils were determined to be similar whether the aliquot distilled was a clear solution or a suspension with solid materials, and these results were similar to those obtained by distilling the entire digest. The precision obtained by the three methods of distillation was similar for the Vertisols but for the Alfisols, distillation of the clear aliquot of the digest was found to be most precis

Plant nutrient contribution by rainfall in the highly industrialized and polluted Patancheru area in Andhra Pradesh

Rainwater contains nutrients and can, in a low-input situation, constitute an important nutrient source for crop production. During 1981–90, rainwater was collected using standardized collection procedures at three different locations at ICRISAT, Patancheru, Andhra Pradesh. Samples were analysed for N, P, K, S, Ca, Mg and Na. Ion concentrations were low and varied from year to year. The mean pH was 7.05. Because the locations were close to each other, there was no significant. variation in the composition of rainwater among the locations. There were negative correlations between the amount of rainfall and the chemical parameters. Phosphorus was positively correlated with N, K, S, Ca, Mg and Na. Patancheru is highly industrialized and its atmosphere will have a bearing on the composition of rainwater. Sulphur fertilizer response experiments should not be carried out at this location. On an average, rainfall at this location contributes, per hectare, 5.8 kg N, 0.4 kg P, 4.8 kg S, 1.7 kg Ca, 1.7 kg Mg and 10.5 kg Na. The increase in N, P and S contribution was higher during 1986–90 than in 1981–8

Soil-Test-Based Balanced Nutrient Management for Sustainable Intensification and Food Security: Case from Indian Semi-arid Tropics

In the semi-arid tropics (SAT), there exists large yield gaps (two- to four-fold) between current farmers’ yields and achievable yields. Apart from water shortages, soil degradation is responsible for the existing gaps and inefficient utilization of whatever scarce water resource is available. On-farm soil fertility testing across different states in Indian SAT during 2001–2012 showed widespread new deficiencies of sulfur (46–96 percent), boron (56–100 percent), and zinc (18–85 percent) in addition to already known phosphorus (21–74 percent) and nitrogen (11–76 percent, derived from soil carbon). Based on these results, a new fertilizer management strategy was designed to meet varying soil fertility needs at the level of a cluster of villages by applying a full nutrient dose if >50 percent fields were deficient and a half dose in the case of fields <50 percent deficient. Improved nutrient management significantly increased crop productivity in groundnut (Arachis hypogaea) (17–86 percent), sorghum (Sorghum bicolor) (30–55 percent), soybean (Glycine max) (10–40 percent), and maize (Zea mays) (10–50 percent) with favorable benefit-cost ratios (1.43–15.2) over farmers’ practice. Nutrient balancing improved nitrogen-fertilizer-use efficiency in respect of plant uptake from soil, transport into grain, use efficiency in food production, and grain nutritional quality. Balanced-nutrient-managed plots showed better post harvest soil fertility. Residual benefits of sulfur, boron, and zinc were observed in up to three succeeding seasons. Results of soil-test-based nutrient-management trials have sensitized policy makers in some states for desired policy orientation to benefit millions of smallholders in the Indian SAT

Soil Nutrient Mapping for On-farm Fertility Management

Feeding the projected population of 9.1 billion globally and 1.6 billion in India by 2050 is one of the greatest challenges of the century, and in this endeavour to ensure future food security, efficient soil nutrient management is crucial (Wani et al., 2003; Sahrawat et al., 2010; Chander et al., 2013). Since the era of the Green Revolution in India in the late 1960s, the focus has been on only three macronutrients, namely nitrogen (N), phosphorus (P) and potassium (K), and this has brought nutrient imbalances and widespread deficiencies of micro and secondary nutrients such as sulfur (S), boron (B) and zinc (Zn) in addition to macronutrients (Wani et al., 2009; Sahrawat and Wani, 2013; Chander et al., 2014). Most farmers and stakeholders are not aware of soil fertility issues and management alongside water and crop management, which is the main reason for large yield gaps in the semi-arid tropics (SAT). In order to ensure future food security and the future of smallholder farmers, science-led interventions are needed to bridge the yield gaps in the SAT. Some pilot initiatives such as the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT)—Andhra Pradesh Rural Livelihood Programme (APRLP) initiative in Andhra Pradesh and the Bhoochetana initiative in Karnataka have shown that soil nutrient mapping is the best entry point activity to enhance productivity and livelihoods through soil-needbased fertility management (Wani et al., 2011; Chander et al., 2013; Sahrawat and Wani, 2013). This chapter therefore focuses on soil fertility management issues and the need of soil nutrient mapping for informed decisions..

Stretching Soil Sampling to Watershed: Evaluation of Soil‐Test Parameters in a Semi‐arid Tropical Watershed

Soil sampling is an integral component of fertility evaluation and nutrient recommendation for efficient use of nutrients in crop production. Little attention has been devoted to evaluating methodology for sampling watersheds under dryland agriculture. A stratified random sampling methodology for sampling the Appayapally watershed in Mahabubnagar district of Andhra Pradesh state in the semi‐arid tropical region of India was adopted and evaluated. The watershed has an area of about 500 ha, with gentle sloping lands (<1% slope), and 217 farmers own land in the watershed. The soils are Alfisols. A total of 114 soil samples were collected from the top 15‐cm layer to represent the entire watershed. Each sample was a composite of 7–8 cores, randomly collected from the area represented by a crop and group of farmers. The soil samples were air dried, ground, and analyzed for pH, electrical conductivity (EC), organic carbon (C), total nitrogen (N), and extractable phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), sulfur (S), zinc (Zn), manganese (Mn), iron (Fe), copper (Cu), and boron (B). Statistical analysis of the results on soil fertility parameters showed that the mean‐ or median‐based results of soil tests performed in the study did not differ significantly when the sample set size varied from 5 to 114 (100% of the population). Our results indicate that farmers' fields in the Appayapally watershed are uniform in the chemical fertility parameters studied, and even a small sample set size can represent the whole population. However, such a sampling strategy may be applicable only to watersheds that are very gently sloping and where fertilizer use is very low, resulting in an overall low fertility in the whole watershed

Macro-benefits from boron, zinc and sulfur application in Indian SAT: a step for grey to green revolution in agriculture. Global Theme on Agroecosystems Report no. 16

The semi-arid tropics (SAT), spread over 11.6 million KM square worldwide, is home to millions of poor people. The soils are low in fertility and degraded to varying extent. The climate is characterized by undependable rainfall, high average temperature and water stress situations for crop growth. The SAT is densely populated and a large number of poor in this region depend on agriculture. The green revolution in Asia bypassed the large tracts of rainfed systems. ICRISAT is committed to improve livelihoods of millions of poor living in the SAT by undertaking agricultural research for impact in a partnership mode. The new watershed model emphasize the management of water as an entry point for improving livelihoods through convergence of natural resource-based activities. ICRISAT's on-farm community watershed research in Asia revealed that the SAT's subsistence agricultural systems have soils depleted not only in macronutrients but also in micronutrients such as zinc and boron, and secondary nutrients like sulfur beyond the critical limits. Widespread (80-100%) deficiencies of micro and secondary nutrients were observed in farmers' field in Andhra Pradesh, India. Substantial increase in yields by 20 to 80% due to micronutrient amendments, and a further increase by 70 to 120% due to micronutrients and adequate nitrogen (N) and phosphorus (P) amendments in a number of crops (maize, sorghum, mung bean, pigeonpea, castor, chickpea) in farmers' fields were observed. Besides minimizing land degradation, increased use efficiency of the inputs such as N and P fertilizers, as well as rainwater, resulted in increased profits and increased productivity. These natural resource management (NRM) interventions are integrated with improved genotypes to harness the full benefits in the watershed. The integrated genetic and natural resource management (IGNRM) approach adopted in watersheds will thus make the grey to green revolution a reality