Soil fertility in flooded and non-flooded irrigated rice systems

The lowland rice system in Asia makes a major contribution to the global rice supply and is often cited as an example of a sustainable system in which two or three crops of rice are grown in sequence under submerged conditions. However, water shortages are becoming critical in some regions for lowland rice cultivation; and there is high potential in exploring rice cultivation under moisture regimes that save water and also increase productivity. The objective of this article therefore is to analyze the consequences of switching growing of rice from flooded to aerobic conditions on soil fertility and its management. Fertility advantages of submerged rice include amelioration of chemical fertility, preferential accumulation of organic matter and improved availability of major, secondary and selected micronutrients, which contribute to the long-term maintenance of soil fertility and sustainability of the lowland rice system. However, the fertility problems under aerobic rice are better addressed with the crop as a component of a cropping system because continuous growing of aerobic rice in sequence does not seem sustainable due to complex, site-specific chemical and biological constraints

Science-led interventions in integrated watersheds to improve smallholders’ livelihoods

Existing large crop yield gaps between farmers’ fields in rainfed areas and the achievable yields are abridged through integrated watershed management during 2002-2007, while improving farmers’ livelihoods also. In addition to water shortages, emerging widespread deficiencies of multiple micro- and secondary nutrients such as sulphur (S), boron (B) and zinc (Zn) along with nitrogen (N) and phosphorus (P) are holding back the productivity potential through inefficient utilization of limited available water. Soil test-based balanced nutrient application of deficient SBZn plus NP in fields in watersheds recorded 70 to 119% (2100 kg ha?1 in maize, 660 kg ha?1 in groundnut, 640 kg ha?1 in mungbean and 1070 kg ha?1 in sorghum) improvement in crop productivity along with additional returns varying from Rs 16,050/- to Rs 28,160/- ha?1 over the farmers’ practice (only NP). Landform management to alleviate waterlogging proved effective intervention to manage high clay Vertisols for higher soybean and groundnut productivity by 13 to 27% (340 to 350 kg ha?1 in soybean and 160 to 250 kg ha?1 in groundnut) over the farmers’ practice. However, the integrated approach of balanced nutrition and landform management plus improved cultivar was the best option in increasing sunflower productivity by 182% (1600 kg ha?1 in sunflower) over farmers’ management (control). Adoption of these soil-water-crop interventions in target watersheds abridged yield gaps by 12 to 96% in groundnut (160 to 1280 kg ha?1), 29 to 100% (240 to 1130 kg ha?1) in pigeonpea and 0 to 100% (0 to 1175 kg ha?1) in chickpea. The impact of watershed interventions was seen in farm-based activities like improved milk production and incomes. The watershed programs alleviated migration in the catchments by improving the five capitals viz. human, financial, social, physical and natural

Carbon Sequestration in Indian Soils: Present Status and the Potential

India’s growing self-sufficiency in food production and food stocks since independence suggest that soils have the capacity to produce. Therefore, a review of Indian soils and their capacity to sequester carbon; and the factors favouring C sequestration under different land uses is in order. Several researchers, especially those in The National Bureau of Soil Survey and Land Use Planning and the International Crops Research Institute for Semi-Arid Tropics monitored the changes in soil organic (SOC) and inorganic (SIC) carbon as influenced by land use in the Indo-Gangetic Alluvial Plains and black soil regions between 1980 and 2005. The results showed an increase in SOC stocks due to turnover of greater plant biomass into the soil. Results of long-term fertilizer experiments with rice-based double or triple cropping systems indicate soil’s capacity to store greater C, and maintain higher C in passive pools and that active fraction of soil C can be used as an indicator of soil health. The inclusion of active pool/labile SOC is expected to improve the performance of Century eco-system model in predicting SOC changes under different climatic conditions. Greenhouse gas emissions from the tropical Indian soils (both zeolitic and non-zeolitic) do not seem to contribute significantly to the global warming potential. The application NPK plus FYM emerged as a cost effective technology for Indian farmers. In view of the potential of C sequestration by major zeolitic and non-zeolitic soils, the present SOC stock of about 30 Pg can be further increased

Balanced nutrient management for crop intensification and livelihood improvement: A case study from watershed in Andhra Pradesh, India

Soil health assessment of farmers’ fields in watershed villages in Medak district, Andhra Pradesh, India showed widespread deficiencies of sulfur (S), boron (B), and zinc (Zn) in addition to organic carbon and phosphorus (P). Participatory on-farm trials on soil test-based application of deficient Zn, B, and S along with nitrogen (N) and P during 2009 to 2012 significantly increased crop yields over farmers’ practice (FP)—by 31% to 45% in chickpea, 15% to 16% in cotton, 12% to 15% in paddy, and 8% to 9% in sugarcane. Total soluble sugars in sugarcane under balanced nutrition (BN) increased by 13%. Residual benefits of S, B, and Zn were observed in succeeding chilly crop (12% higher yield). Benefit to cost (B:C) ratios of BN ranged between 2.8 to 8.5 in chickpea, 2.6 to 4.4 in cotton, 2.3 to 2.9 in paddy, and 7.1 to 11.4 in sugarcane, indicating economic feasibility for scaling-up

Integrated nutrient management using deoiled Jatropha cake for sustained and economic food production

With growing environmental and energy concerns, Jatropha plantations are promoted in degraded/waste lands for the biodiesel production. Nutrient rich nonedible deoiled seed cake, a by-product of Jatropha left out after oil extraction was evaluated at the ICRISAT centre at Patancheru, India as an environment friendly source of nutrients for rainy season maize and soybean followed by postrainy chickpea in rainfed systems. Deoiled cake as partial (50%) or full replacement of recommended basal nitrogen (N) was found superior in terms of increased crop yield over the equivalent chemical fertilizers treatments. Highest yield and net returns under full replacement of basal N for maize, while under 50% basal N replacement in case of soybean and chickpea crops were recorded by 8 to 27% in grain yield and 10 to 28% in straw yield. Deoiled Jatropha cake as a full replacement of N dose in maize also recorded higher N uptake and use efficiency in maize than chemical N source treatment along with increased organic C and nutrient contents in post-harvest soil samples. This study revealed the benefits of Jatropha deoiled seed cake as a good source of plant nutrients and soil organic C in the semi-arid tropics in addition to enhanced C sequestration under Jatropha plantation on degraded waste lands

How to manage salinity in irrigated lands: a selective review with particular reference to irrigation in developing countries

This paper presents a conceptual framework for water accounting and provides generic terminologies and procedures to describe the status of water resource use and consequences of water resources related actions. The framework applies to water resource use at three levels of analysis: a use level such as an irrigated field or household, a service level such as an irrigation or water supply system, and a water basin level that may include several uses. Water accounting terminology and performance indicators are developed and presented with examples at all the three levels. Concepts and terminologies presented are developed to be supportive in a number of activities including: identification of opportunities for water savings and increasing water productivity; developing a better understanding of present patterns of water use and impacts of interventions; improving communication among professionals and communication to non-water professionals; and improving the rationale for allocation of water among uses. It is expected that with further application, these water accounting concepts will evolve into a robust, supporting methodology for water basin analysis

Extractable soil nutrient effects on feed quality traits of crop residues in the semiarid rainfed mixed crop-livestock farming systems of Southern India

In the mixed crop–livestock systems, while general relation among feed quality, productivity and soil nutrient management have been reported, information on the effects of extractable soil nutrients on crop residue (CR) feed quality traits is scarce (e.g. in semiarid regions of Karnataka, India). In view of the increasingly important role of CR as feed components, in these farming systems, generating such information is a relevant research issue for sustainable development. Here, we report the occurrence and strength of relationships among extractable nutrients in soils and CR feed quality traits, and the effects of improved nutrients input on feed availability and feed quality of CR. Soil samples were collected from farmers’ fields in the semiarid zone of Karnataka and analyzed for available phosphorus (P), potassium (K), sulphur (S), zinc (Zn) and boron (B) using standard laboratory methods. Soil test results were clustered as low, medium or high based on the level of nutrient concentration. Four major farming systems involving nine crops and 419 farms were selected for on-farm trials. Under every sample farm, a plot with farmer’s practice (control) and improved fertilizer inputs (combined application of nutrients found deficient by soil testing) were laid. Performance of crops was recorded. Samples were collected for CR feed quality trait analysis using Near Infrared Reflectance Spectroscopy. The result showed that for cereal and oil crops, extractable soil S was significantly negatively associated with anti-feed quality traits such as neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) (P < 0.01), but significantly positively related to metabolizable energy (ME) and in vitro digestibility (P < 0.01). Extractable B and K levels were associated positively and significantly with NDF, ADF and ADL for oil crops and cereals. Crop level associations, for most crops, showed similar trend. Improved fertilizer inputs affected CR yield much more than it did the quality. It increased ME productivity (ME ha−1) and thereof the potential milk yield ha−1 by as high as 40 % over the control. Therefore, balanced nutrient inputs on crop land positively impact productivity of the livestock compartment of mixed crop–livestock farming system, and this knowledge can build on the currently perceived need and benefits of balanced nutrient replenishment in crop–livestock system