S. S. Kukal

Halting the Groundwater Decline in North-West India—Which Crop Technologies will be Winners?

Increasing the productivity of the rice–wheat (RW) system in north-west India is critical for the food security of India. However, yields are stagnating or declining, and the rate of groundwater use is not sustainable. Many improved technologies are under development for RW systems, with multiple objectives including increased production, improved soil fertility, greater input use efficiency, reduced environmental pollution, and higher profitability for farmers. There are large reductions in irrigation amount with many of these technologies compared with conventional practice, such as laser land leveling, alternate wetting and drying (AWD) water management in rice, delayed rice transplanting, shorter duration rice varieties, zero till wheat, raised beds, and replacing rice with other crops. However, the nature of the irrigation water savings has seldom been determined. It is often likely to be due to reduced deep drainage, with little effect on evapotranspiration (ET). Reducing deep drainage has major benefits, including reduced energy consumption to pump groundwater, nutrient loss by leaching, and groundwater pollution. The impacts of alternative technologies on deep drainage (and thus on irrigation water savings) vary greatly depending on site conditions, especially soil permeability, depth to the watertable, and water management. More than 90% of the major RW areas in north-west India are irrigated using groundwater. Here, reducing deep drainage will not “save water” nor reduce the rate of decline of the watertable. In these regions, it is critical that technologies that decrease ET and increase the amount of crop produced per amount of water lost as ET (i.e., crop water productivity, WPET) are implemented. The best technologies for achieving this are delaying rice transplanting and short duration rice varieties. The potential for replacing rice with other crops with lower ET is less clear.

Improving Water Productivity of Wheat-Based Cropping Systems in South Asia for Sustained Productivity

Abstract Serious water deficits are threatening agricultural sustainability in many regions of the South Asia (SA). While the increase in crop production of irrigated rice–wheat system in SA has been impressive since the 1970s, the low water productivity (WP) has led to the depletion of surface water and groundwaters. In this chapter we have discussed the availability of water resources in SA, identified the positive effects of soil and water management and crop genetic improvement on WP, and then described knowledge gaps and research priorities to further improve the WP with special emphasis on wheat-based cropping systems in irrigated and rainfed regions of SA. A single approach would not be able to tackle the forthcoming challenge of producing more food and fiber with limited or even reduced available water. Integrating irrigation water-saving techniques (water-saving irrigation methods, deficit irrigation, modernization of irrigation system, etc.) with agronomic and soil manipulations viz., optimum irrigation scheduling, direct-seeded rice, alternate wetting and drying in puddle transplanted rice, raised bed planting, crop diversification, conservation tillage, crop residue management, and conjunctive use of good quality (canal) water. Improved soil water management practices for rainfed regions include reducing runoff, rainwater harvesting and recycling, conserving rainwater in the root zone by reducing evaporation losses, and optimal nutrient management. The low WP in farmer’s fields compared with well-managed experimental sites indicates the need for more efforts to transfer water-saving technologies to the farmers. In future we need to increase scientific understanding of the effects of agronomic management on WP across various soil and climate conditions; improve irrigation practices (timing and amounts) and methods (drip and sprinkler) based on real-time monitoring of water status in soil-crop systems; and maximize WP by managing water resources and allocation at regional scales in wheat-based cropping systems.

Splash erosion and infiltration in relation to mulching and polyvinyl alcohol application in semi-arid tropics

Splash erosion, caused due to structural instability, leads to the formation of soil crust, which hampers infiltration rate of soils and affects the germination of seeds. To ensure the optimum infiltration rate and better germination, it is important that splash erosion and crusting are prevented. A study was carried out in sandy loam and silt loam soils to monitor the splash loss and infiltration rates in relation to application of straw mulch and polyvinyl alcohol (PVA) under simulated rainfall. The treatments included spreading chopped wheat straw on tilled soil at a rate of 6 t ha−1 and spraying of 0.1 and 0.5% PVA solutions on tilled soil surface, in addition to an untreated tilled soil as control. The treatments were replicated four times. The straw mulch application decreased the mean splash loss by 68% compared to unmulched soil. The mean basic infiltration rate (IR) measured, as an index of soil crusting, was 54% higher in soils with mulch cover than in soils without mulching. The average splash loss decreased by 56% with 0.1% PVA and 84% with 0.5% PVA application compared to untreated soil. The mean basic IR did not increase significantly, when treated with 0.1% PVA solution compared to untreated soils, whereas 0.5% PVA application increased the basic IR by 77%. The effect of mulch and PVA in decreasing splash loss and increasing IR was more effective in sandy loam than in silt loam.

Erodibility of Sandy Loam Aggregates in Relation to Their Size and Initial Moisture Content Under Different Land Uses in Semi-Arid Tropics of India

Soil erodibility, an index of ease of detachment of soil aggregates due to beating action of falling raindrops, is generally characterized through soil physical properties-based indices, which may not be applicable universally. The water stability of aggregates as determined by simple shaking under water though a more reliable index, does not simulate the actual field situation. The present study was conducted to determine the erodibility of natural, undisturbed soil aggregates from agricultural, forest, pasture, and eroded land uses from Punjab, India, in relation to their size and moisture status, using simulated raindrops in the laboratory. The mean EISRT (single raindrop technique-based erodibility index) was least under pastures followed by forest, agricultural, and eroded soils. The erodibility of aggregates increased significantly with an increase in aggregate size. Increasing the initial moisture content of aggregates resulted in increased erodibility with air-dry aggregates being the least erodible and the saturated ones the most. The effect of land use on soil erodibility was more pronounced when the aggregates were air-dried. The bigger (4.5 mm) raindrops did not differentiate the erodibility of aggregates from different land uses due to higher kinetic energy of the individual raindrops. The total number of raindrops used to completely disrupt an aggregate decreased with an increase in the size of raindrops. At saturation, even the aggregates from the pasture lands became unstable and their erodibility increased. Thus, the erodibility of bigger (> 10 mm) saturated aggregates was higher than the smaller saturated aggregates.

Evaluation of Different Organic Growing Media for Growth and Flowering of Petunia

Studies were carried out at Punjab Agricultural University Landscape Nursery from November 2009 to July 2010 to evaluate the different soil-based and soilless media compositions on growth and flowering of petunia hybrids. Different media compositions comprising leaf mold, sewage sludge, vermicompost, farmyard manure, cocopeat, and soil were evaluated in definite ratios to select an ideal potting media for raising potted (6-inch pots) petunia plants. Results revealed that media composition M6 was the best potting media to raise petunia plants. Petunia plants raised in this media [soil + sewage sludge (K) (2:1)] exhibit maximum (55.3 days) number of days of flowering duration, maximum (129.5 days) number of days to flowering withering, recorded minimum (74.2 days) number of days to bud emergence, and counted more (30.0) number of buds and maximum (15.0) number of branches. This media composition was observed to be ideal for raising petunia seedlings to full-grown floriferous potted petunia plants with all the desirable characteristics essential for a specimen display.

Direct Seeded Rice in South Asia

Rice–wheat is the major cropping system occupying 13.5 million ha in the Indo-Gangetic Plains of South Asia. Conventional puddle transplanted system of rice is water, capital and energy intensive. This system leads to structural deterioration of the soil. Furthermore, aeration stress due to hard pan formation during the rice season modifies wheat yields. Technical training is required to grow mat type nursery and operating of transplanter put mechanical transplanting to a second option. Direct seeding of rice with zero or reduced tillage is a viable option for sustainable rice production, if problems of weeds, micronutrients deficiency, nematodes and development of aerobic variety are addressed. Further, direct seeded rice reduces emission of greenhouses gases. We review here the performance of direct seeding of rice at texturally divergent soils in different agroclimatic regions; and major problems encountered.

Root Growth and Soil Water Dynamics in Relation to Inorganic and Organic Fertilization in Maize–Wheat

Agricultural productivity is increasingly becoming dependent upon soil fertility, which is generally thought to be supplemented through the application of nutrients mainly through inorganic fertilizers. The present study aims to characterize the soil physical environment in relation to long-term application of farmyard manure (FYM) and inorganic fertilizers in a maize–wheat cropping system. The treatments in both the maize and wheat systems included a control (without any fertilizer or FYM), FYM (farmyard manure at 20 t ha−1), N100 (nitrogen at 100 kg ha−1), N100P50 (nitrogen and phosphorus at 100 and 50 kg ha−1), and N100P50K50 (nitrogen, phosphorus, and potash at 100, 50, and 50 kg ha−1). The treatments were replicated four times in a randomized complete block design in sandy loam soil. The root mass density in surface layers of both the crops was lower in FYM and higher in inorganic fertilizer plots. The root length density was found to be highest in FYM-treated plots and lowest in control plots. The periodic soil matric suction during wheat following maize remained highest in FYM plots followed by that in N100 plots in all the layers. The soil water storage of wheat at harvest (rice–wheat) was highest (21.1 cm) in control and lowest (17.8 cm) in FYM-treated plots. The soil water status, root growth, and crop performance improved with balanced fertilization.

Standardization of Automated Vario EL III CHNS Analyzer for Total Carbon and Nitrogen Determination in Soils

Carbon (C) and nitrogen (N) determination with traditional methods is more laborious and time-consuming than automated analyzers. Microprocessor-based technologies led to the development of automated analyzers and have reduced the time of analysis. However, these need to be standardized with respect to weight and mesh size of plant/organic material sample used. For standardization of Vario EL III carbon (C), hydrogen (H), nitrogen (N), and sulfur (S) analyzer for the particle size and amount of sample, laboratory studies were carried out for C and N determination by CHNS analyzer in comparison to the traditional methods for different categories of organics such as green manure (cowpea), crop residues (rice straw), animal residues (farmyard manure), and industrial by-product (press mud). Organic samples of <0.25-mm size resulted in greater amounts of C and N with both CHNS analyzer and traditional methods than with other size groups. The C and N contents were greater with a sample weight of 5 than with 10 mg.

Chapter 6 – Effective Management of Scarce Water Resources in North-West India

North-west (NW) India is among the most productive agricultural regions of the world because the region is well endowed with both surface and ground water resources, deep alluvial soils, and a favorable climate for year-round crop production. But injudicious use of surface and groundwater has created many problems including groundwater depletion, waterlogging, salinization, and degradation of water quality. Increasing water scarcity is a major threat to the agricultural production of NW India. However, there are many water resource management strategies to help address water scarcity, such as reducing water losses, conjunctive use of surface and ground water, and recharge of ground water. In addition to these strategies, improved crop water management technologies can also help to reduce water input by avoiding the wastage of water by deep drainage, seepage, runoff, evaporation, etc. Integrated use of water resource management techniques, along with improved crop water management technologies, can help to increase water productivity and sustain or increase production.

TILLAGE AND ESTABLISHMENT METHOD IMPACTS ON LAND AND IRRIGATION WATER PRODUCTIVITY OF WHEAT–RICE SYSTEM IN NORTH-WEST INDIA

The resource conservation technologies (RCTs), being advocated for countering the threat to the sustainability of wheat–rice cropping system (RWCS) in the north–west (NW) Indo-Gangetic Plains (IGP) of India, have been evaluated mostly for the individual crops, without depicting the impact of these technologies on the succeeding or preceding crop. A study was thus conducted during 2012–2014 in NW India to assess the land and irrigation water productivity (WP I ) of RWCS under different establishment and conservation tillage techniques in a sandy-loam soil (coarse loamy, calcareous, mixed, hyperthermic Typic Ustochrept). The treatments included zero (ZTW) and conventional (CTW) tillage in wheat as main plot, establishment methods (direct seeded (DSR) and mechanically transplanted rice (MTR)) as sub-plot and tillage in rice viz. puddle (PR), dry (CTR) and zero (ZTR) tillage as sub–sub plot treatments, replicated thrice in split–split plot design. The land productivity of RWCS was significantly lower in ZTW plots than in CTW plots. The residual effect of tillage in wheat on rice productivity was distinct during the second year of study, when the CTW plots recorded significantly higher (17.5%) rice yield than the ZTW plots. The productivity of the cropping system with DSR was statistically similar to that with MTR. The WP I of RWCS increased in the order ZTW–DSR–ZTR25