Raj K. Gupta

The role of conservation agriculture in sustainable agriculture

The paper focuses on conservation agriculture (CA), defined as minimal soil disturbance (no-till, NT) and permanent soil cover (mulch) combined with rotations, as a more sustainable cultivation system for the future. Cultivation and tillage play an important role in agriculture. The benefits of tillage in agriculture are explored before introducing conservation tillage (CT), a practice that was borne out of the American dust bowl of the 1930s. The paper then describes the benefits of CA, a suggested improvement on CT, where NT, mulch and rotations significantly improve soil properties and other biotic factors. The paper concludes that CA is a more sustainable and environmentally friendly management system for cultivating crops. Case studies from the rice–wheat areas of the Indo-Gangetic Plains of South Asia and the irrigated maize–wheat systems of Northwest Mexico are used to describe how CA practices have been used in these two environments to raise production sustainably and profitably. Benefits in terms of greenhouse gas emissions and their effect on global warming are also discussed. The paper concludes that agriculture in the next decade will have to sustainably produce more food from less land through more efficient use of natural resources and with minimal impact on the environment in order to meet growing population demands. Promoting and adopting CA management systems can help meet this goal.

Do organic amendments improve yield trends and profitability in intensive rice systems

Opinions differ as to the importance of organic amendments (OA) for sustaining crop productivity in the intensive, irrigated rice systems of Asia. Our objectives were to (1) quantify the effects of farmyard manure (FYM) and straw incorporation on yield trends in long-term experiments (LTEs) with rice–rice (R–R) (Oryza sativa L.) and rice–wheat (R–W) (Triticum aestivum L.) systems and (2) assess the potential effects of OA on profitability, taking into account long-term effects on yield. We analyzed yield trends in 25 LTE (seven R–R, 18 R–W systems) across a wide geographical range in Asia. Three main conclusions emerged from this analysis. First, application of either manure or straw did not improve grain yield trends in R–R and R–W cropping systems. Second, depending on socio-economic conditions, use of manure or straw in these cropping systems may be profitable, provided these OA are used as a complement to a recommended dose of inorganic NPK (i.e. organic materials should not be used as the primary nutrient source). Third, current experimental designs to assess the suitability of OA need to be improved in order to allow a better comparison of the relative advantages of inorganic and organic fertilizers. The major shortcoming of current designs is that they do not properly adjust mineral fertilizer rates in the inorganic treatments to account for the macronutrient input from OA. Thus, our tentative estimates of the profitability of OA may be overstated.

Conservation Agriculture in South Asia

The Green Revolution era focused on enhancing the production and productivity of rice and wheat. New challenges demand that the issues of efficient resource use and resource conservation receive high priority to ensure that past gains can be sustained and further enhanced to meet the emerging needs. Extending some of the resource-conserving interventions developed for wheat to rice culture is a major challenge for researchers and farmers alike. The present paper shares recent research experiences on resource conservation technologies involving tillage and crop establishment options and associated agronomic practices which enable farmers in reducing production costs, increase profitability and help them move forward in the direction of adopting conservation agriculture.

Water saving in rice-wheat systems

Abstract Water shortage is a major constraint to sustaining and increasing the productivity of rice-wheat systems. Saving water can be elusive in that reducing seepage, percolation and runoff losses from fields does not necessarily save water if it can be recaptured at some other temporal or spatial scale, for example by groundwater pumping. Many technologies appear to save substantial amounts of water through reducing irrigation water requirement, but whether these are true water savings is uncertain as components of the water balance have not been quantified. Such technologies include laser levelling, direct drilling, raised beds, non-ponded rice culture and irrigation scheduling. It is questionable whether puddling saves water. Reducing non-beneficial evaporation losses is a true water saving, and optimal planting time of rice to avoid the period of highest evaporative demand and changing to non-ponded rice culture can save significant amounts of water. However, moving away from puddled, ponded to more aerobic rice culture sometimes brings new production problems. Furthermore, farmers faced with unreliable water supplies need to store water on their fields as insurance, and puddling assists retention of water during the rice crop. Rehabilitation and improvement of canal and power systems in Asia, funded by charging according to use, are required to facilitate adoption of many water saving technologies. Australian farmers pay fixed plus volumetric charges for water to cover the cost of infrastructure and operation of irrigation systems, which are continuously being improved to provide water on demand and minimise losses. They are able to plan their plantings based on knowledge of the likely amount of irrigation water available each season and crop water use requirement, and thus avoid wasting water and financial loss by overplanting and crop failure. Such approaches have the potential to increase production and water productivity in Asia, however the challenge would be to apply them in an equitable way that benefits many millions of subsistence farmers.

Gene networks in hexaploid wheat: interacting quantitative trait loci for grain protein content.

In hexaploid wheat, single-locus and two-locus quantitative trait loci (QTL) analyses for grain protein content (GPC) were conducted using two different mapping populations (PI and PII). Main effect QTLs (M-QTLs), epistatic QTLs (E-QTLs) and QTL × environment interactions (QE, QQE) were detected using two-locus analyses in both the populations. Only a few QTLs were common in both the analyses, and the QTLs and the interactions detected in the two populations differed, suggesting the superiority of two-locus analysis and the need for using several mapping populations for QTL analysis. A sizable proportion of genetic variation for GPC was due to interactions (28.59% and 54.03%), rather than to M-QTL effects (7.24% and 7.22%), which are the only genetic effects often detected in the majority of QTL studies. Even E-QTLs made a marginal contribution to genetic variation (2.68% and 6.04%), thus suggesting that the major part of genetic variation is due to changes in gene networks rather than the presence or absence of specific genes. This is in sharp contrast to the genetic dissection of pre-harvest sprouting tolerance conducted by us earlier, where interaction effects were not substantial, suggesting that the nature of genetic variation also depends on the nature of the trait.

Response of nine forage grasses to saline irrigation and its schedules in a semi-arid climate of north-west India

Traditionally, the degraded lands in arid and semi-arid regions are left for pastures but their forage productivity is low, unstable and unremunerative. Often this results in acute shortages of fodder during the post-monsoon period that can perhaps be partly overcome if the limited saline ground-water resources are effectively utilized to supplement water supplies. Thus, a field experiment was conducted during 1993–1997 on a calcareous soil in a semi-arid part of north-west India (average rainfall 350 mm/annum) to evaluate the suitability of forage grasses to saline irrigation (ECiw 8.5–10.0 dS/m) and optimize its schedule. Grass species included in this experiment were Brachiaria mutica Stapf. Cenchrus setigerus Vahl. Chloris gayana Kunth, Cymbopogon flexuosus, Cynodon dactylon Pers. Echinochloa colonum Link. Panicum antidotale Retz., P. coloratum Linn., P. laevifolium Hack., P. maximum Jacq. (Local wild), P. maximum Jacq. (Cultivated) and P. virgatum. Species those were identified to be the most promising included Panicum laevifolium and P. maximum (both local wild and cultivated) with an annual forage production of 3.43–4.23 Mg/ha. The overall reduction in forage yield with saline irrigation equalled 29 per cent when compared with canal water (ECiw 0.4 dS/m). Scheduling saline irrigation based on climatological approach, i.e. when the ratio of depth of irrigation water (Diw) and cumulative open pan evaporation (CPE) equalled 0.4, was observed to be optimal whereas increased salt accumulation nullified the benefits of enhanced water supplies (Diw/CPE=0.8). Two of the definite advantages of irrigated forages were about three–four-fold increase in productivity as compared with natural/seeded pastures and extension of production period to those of conventional shortages, i.e. during summer months (April–June) when the most nomad populations are forced to migrate to traditionally irrigated areas. Thus, it was concluded that saline water use strategies for rehabilitating arid lands with above grass species would not only render these degraded lands be more productive but also ensure conservation and improvement for long-range ecological security of these lands.

Sustainability of the rice-wheat cropping system: issues, constraints, and remedial options

Abstract The rice-wheat cropping system of the Indo-Gangetic Plains (IGP) has contributed tremendously to food security of the region. However, of late there has been a significant slowdown in yield growth rate of this system and the sustainability of this important cropping system is at stake. A decline in soil productivity, particularly of organic C and N, a deterioration in soil physical characteristics, a delay in sowing of wheat, and decreasing water availability are often suggested as the causes of this slowdown in productivity. Therefore, a paradigm shift is required for enhancing the systems productivity and sustainability. Resource-conserving technologies involving zero-or minimum tillage with direct seeding, improved water-use efficiency, innovations in residue management to avoid straw burning, and crop diversification should assist in achieving sustainable productivity and allow farmers to minimize inputs, maximize yields, conserve the natural resource base, reduce risk due to both environmental and economic factors, and increase profitability.

Atretic cephalocele: contribution of magnetic resonance imaging in preoperative diagnosis.

We describe a case of parietal cephalocele. MRI and MR venography were useful for accurate anatomical depiction. We speculate on developmental pathogenesis in the context of the literature available.

Crop sensors for efficient nitrogen management in sugarcane: potential and constraints

A real-time crop sensor for site specific input application is the new innovation in the field of precision agriculture. At least three different type of crop sensors,viz.. Soil Doctor, N-Senior and Green Seeker have been used in different field crops. The key advantage of all these systems is that they do not need recommendation maps. However, no published data is available on Soil Doctor adoption by farmers due to company’s aggressiveness for protective patent rights. The N-Sensor is being used mainly for wheat and other small grain crops. However, one of the key limitations of N-Sensor is ambient light source. Handheld Green Seeker sensor is the latest addition to the list of crops sensors. The active light source is a major advantage of the Green Seeker sensor. Our preliminary observations on NDVI in relation to canopy development and crop growth in sugarcane are very encouraging and we envisage a potential scope of Green Seeker optical sensor for monitoring crop growth in order to adjust timing and dose of N application for maximizing cane and sugar productivity.

Sustainability Considerations in Wheat Improvement and Production

Abstract This article describes the global wheat mega-environments and consequently need for different types of wheat germplasm. The breeding programs worldwide have targeted yield potential gains as one of their major objectives. The yield gains have been variable, but consistently increasing until the end of the last century. However, in general, there has been a large benefit (estimated between 2 to 6 billion US