Virender Sardana

Productivity and Sustainability of the Rice–Wheat Cropping System in the Indo-Gangetic Plains of the Indian subcontinent: Problems, Opportunities, and Strategies

Abstract Rice and wheat are the staple foods for almost the entire Asian population and therefore they occupy a premium position among all food commodities. The era of the Green Revolution started during the early 1970s with wheat and rice and since then the rice–wheat cropping system of the Indo-Gangetic Plains has played a significant role in the food security of the region. However, recent years have witnessed a significant slowdown in the yield growth rate of this system and the sustainability of this important cropping system is at risk due to second-generation technology problems and mounting pressure on natural resources. Traditional cultivars and conventional agronomic practices are no longer able to even maintain the gains in productivity achieved during the past few decades. Demand for food is increasing with the increasing population and purchasing power of consumers. The rice–wheat cropping system is labor-, water-, and energy-intensive and it becomes less profitable as these resources become increasingly scarce and the problem is aggravated with deterioration of soil health, the emergence of new weeds, and emerging challenges of climate change. Therefore, a paradigm shift is required for enhancing the systems productivity and sustainability. Resource-conserving technologies involving zero- or minimum-tillage in wheat, dry direct seeding in rice, improved water- and nutrient-use efficiency, innovations in residue management to avoid straw burning, and crop diversification should assist in achieving sustainable productivity and allow farmers to reduce inputs, maximize yields, increase profitability, conserve the natural resource base, and reduce risk due to both environmental and economic factors. A number of technological innovation and diversification options have been suggested to overcome the systems sustainability problems but some of them have not been fully embraced by the farmers as these are expensive, knowledge-intensive, or do not fit into the system and have resulted in some other unforeseen problems. Different concerns and possible strategies needed to sustain the rice–wheat cropping system are discussed in this review on the basis of existing evidence and future challenges.

Modeling Sunflower Productivity and Profitability in Relation to Adequate and Limited Sulphur Availability under Semiarid Irrigated Conditions

Inadequate and/or imbalanced fertilization has been identified as one of the critical bottlenecks holding oilseeds production and productivity. Sustainable production requires efficient use of inputs maintaining optimum yield and high quality product. The present study aims at defining the quantitative relationship between the fertilizer S applied and the sunflower yield obtained using a polynomial function. The analysis was done to allocate the S fertilizer for maximization of net profit over fertilizer cost depending on the availability of the fertilizer. The results indicated that the cost effective economically optimum dose of sulphur for sunflower cultivation was found to be 36.70 kg S/ha under its full availability. The expected sunflower yield at this dose was worked out to be 2.619 t/ha. However, it is advisable to uniformly distribute the fertilizer to all over the cultivable area under its limited availability for exploiting the desired yield potential and maximum net monetary returns.

Nutrient Management for Sustaining Productivity of Sunflower-Based Cropping Sequence in Indian Semiarid Regions

ABSTRACT A comprehensive long-term study (2006–2010) was undertaken to develop a balanced and integrated nutrient supply system for sunflower-based cropping sequence considering the efficient utilization of residual and cumulative soil nutrient balance along with added fertilizers by the crops grown in rotation. The fertilizer application was done in potato and sunflower while greengram was raised as such on their residual effect. Significant response in yield was observed with 150% of the recommended nitrogen, phosphorus and potassium (NPK) or inclusion of farmyard manure (FYM) with the recommended NPK in the cropping sequence indicating 6.2–7.0% gain in system productivity over the existing recommendations. Each additional unit of P and K nutrition prompted system productivity by 18.9 and 11.0 kg kg−1 of applied nutrient, respectively. Apparent yield decline was observed in K and PK omission plots to the extent of 15.8 and 27.4% in potato, 10.5 and 23.9% in sunflower and 4.2 and 8.3% in greengram, respectively, compared to the recommended fertilization. The superiority of the FYM along with the recommended NPK (potato/sunflower) was evident on the overall profitability and sustainability of the system, highlighted by the significantly higher productivity (7.16 t SFEY ha−1), sustainability yield index (SYI; 0.76), production efficiency (PE; 27.85 kg SFEY ha−1 day−1) and net returns (2520 USD ha−1) with a B:C ratio of 2.91. Apparent change in potassium permanganate (KMnO4)-N was negative in all the treatments while N and P balance was positive with 150% NPK fertilization. Nutrient uptake exceeded the replenishment with 100% NPK application and maintained net negative soil nutrient stock for all the primary nutrients, indicating the need for revalidation of the existing recommendations in the system perspective. Conspicuous improvement in residual soil fertility in terms of maximum buildup of soil organic carbon (14%) and enhancement in soil KMnO4-N (4.2%), Olsen-P (19.4%), ammonium acetate (NH4OAc)-K (5.8%) and dehydrogenase enzyme activity (44.4%) was observed in FYM-treated plots over the initial values. The study suggested that the inclusion of legumes and FYM application with the recommended NPK in potato-sunflower cropping sequence will sustain the system’s productivity through the efficient use of nutrients, enhanced microbial activity and improved soil health while combating escalating prices of fertilizers as well as environmental issues in the Indo-Gangetic plains of India and similar environments.

Modelling approach to optimize sulphur fertilization in irrigated sunflower under semi-arid conditions in north-west India

Sulphur fertilization assumes substantial influence in improving the yield and quality of oilseed crops. The relationship between sunflower seed yield and sulphur dose applied was determined using quadratic model and the economically optimum sulphur dose was calculated via marginal analysis for yield maximization and profit over fertilizer cost. Economically optimum dose of sulphur for sunflower was found to be 32.99 and 38.95 kg/ha under semi-arid irrigated conditions during 2008 and 2009, respectively. Over-fertilized condition of S for maximum output did not bring out any significant advantage viewing almost identical seed yield both at physical and economic optimum of S indicating a saving of S from 2.8 to 4.0 kg/ha.