Conservation Agriculture for Restoration of Degraded

0 downloads 0 Views 2MB Size Report
and it has been estimated that globally 60–90 peta gram (Pg) of soil organic carbon (SOC) ... Inappropriate agricultural practices include excessive tillage and ... groundwater beyond the safe yield of the aquifer), commercial development ... While advancing food and nutritional security, adoption of restorative land use and ...

Conservation Agriculture for Advancing Food Security in Changing Climate Vol. 1 (2018) : 1-35 Editors : Anup Das, KP Mohapatra, SV Ngachan, AS Panwar, DJ Rajkhowa, Ramkrushna GI and Jayanta Layek Today & Tomorrow’s Printers and Publishers, New Delhi - 110 002, India

Conservation Agriculture for Restoration of Degraded Land and Advancing Food Security Anup Das*, KP Mohapatra and SV Ngachan ICAR Research Complex for NEH Region, Umiam, Meghalaya *

e-mail:[email protected]

Introduction Global food demand is increasing rapidly, as are the environmental impacts of agricultural expansion. A 100–110% increase in global crop demand from 2005 to 2050 is forecasted. Quantitative assessments indicated that the environmental impacts of meeting this demand depend on how global agriculture expands. If current trends of greater agricultural intensification in richer nations and greater land clearing (intensification) in poorer nations were to continue, ~1 billion ha of land would be cleared globally by 2050, with CO2-C equivalent greenhouse gas (GHG) emissions reaching ~3 giga ton (Gt)/year (y) and N use ~250 million tonne (mt)/y by then. In contrast, if 2050 crop demand is met by moderate intensification focused on existing croplands of under-yielding nations, adaptation and transfer of high-yielding technologies to these croplands, and global technological improvements, land clearing of only ~0.2 billion ha is forecasted, greenhouse gas emissions of ~1 Gt/y, and global N use of ~225 mt/y (Tillman et al., 2011). Thus, conservation effective management practices could substantially advance food security with minimal environmental impacts. The quantum jump in food pro­duction and elimination of mass starvation have been driven by farm mechanization, introduction of inputresponsive high yielding varieties, use of chemical fertilizers, herbicides and pesticides, and increase in irrigation. Some of the notable consequences of the agricultural development in the last five decades are increase in (1)


Today & Tomorrow’s Printers and Publishers

human population from 3 to 7.3 billion (United Nations 2014); (2) increase in atmospheric concentration of carbon dioxide (CO2) from 316 ppm to 400 ppm (IPCC, 2014); (3) global temperature by 0.12°C (0.22°F) per decade (IPCC, 2014); (4) problems of soil degradation by erosion, salinization, depletion of soil organic matter (SOM), and nutrient imbalance (Bai et al., 2008). Yet, food production must be increased by another ~ 1 billion ton by 2050 to feed the burgeoning population, while restoring the degraded soils and ecosystems, reducing net anthropogenic emissions, and improving the environment (Lal et al., 2015a). Continuous and intensive tillage practices lead to loss of soil carbon and it has been estimated that globally 60–90 peta gram (Pg) of soil organic carbon (SOC) was lost during the last several decades (Lal, 1999). Adoption of traditional management practices including deep tillage and inversion combined with the removal of crop residues has resulted in SOC depletion which has exacerbated soil degradation and diminished the physical, chemical and biological properties of the soil (Lal, 2014). Intensive cropping over the years encourages oxidative losses of C due to continuous soil disturbance, while cropping results in large scale addition of C to the soil through addition of crop residues which either results in net addition or depletion of soil C stocks (Majumder et al., 2008). The finite and fragile soil resources, especially of the ecologically sensitive eco-regions of hill lands, must be used, improved and restored through adoption of restorative land uses and recommended best management practices. Soil must never be taken for granted because “soil is life and life is soil” (Lal, 2015b). There are three strategies of lowering CO2 emissions to mitigate climate change (Schrag, 2007) of which sequestering CO2 from point sources or atmosphere through engineering techniques, recarbonization of the biosphere through improved land use and science-based agriculture are important. Methane (CH4 ) and nitrous oxide (N2 O) have greater greenhouse effects than CO2, CH4 has approximately 20 times higher global warming potential than CO2, while N2O is approximately 310 times more potent than CO2 (Pisante et al., 2010). Concentrations of these gases are increasing at 0.4, 3.0 and 0.22% per year, respectively (Battle et al., 1996). CO2, CH4 and N2O are the important greenhouse gases (GHG) contributing 60, 15 and 5%, respectively, towards enhanced global warming (Watson et al., 1996). Efforts to increase soil carbon (C) storage through conservation management have gained momentum in the last few decades, particularly to counter the effects of global warming (Sarkhot et al., 2012), and to reduce the net anthropogenic emissions. Avoiding puddling, alternate wetting and drying approach would reduce the CH4, but also the N2 O

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


emissions (Salas, 2010). Hence, the agronomic management in conventional crop production systems need to be looked into critically and understood with an overall strategy of: (i) producing more food with reduced risks and costs, (ii) increasing input use-efficiency, viz. land, labour, water, nutrients, and pesticides, (iii) improving and sustaining quality of natural resource base, and (iv) mitigating emissions and greater resilience to changing climates (Sharma and Singh, 2014). CA in Indian context Food grain production of India has increased from 50.8 mt in 195051 to over 272 mt in 2016-17. This however, had further consequences, including loss of plant biodiversity and environmental pollution. Widespread land degradation caused by inappropriate agricultural practices has a direct and adverse impact on the environment, food and livelihood security of farmers. Inappropriate agricultural practices include excessive tillage and use of heavy machinery, excessive and imbalanced use of inorganic fertilizers, poor irrigation and water management techniques, pesticides overuse, inadequate crop residue and/or organic carbon inputs and poor crop planning. Agricultural activities and practices can cause land degradation in a number of ways depending on land use, crops grown and management practices adopted. Some of the common causes of land degradation by agriculture include cultivation in fragile deserts and marginal sloping lands without any conservation measures, land clearing and deforestation, depletion of soil nutrients due to poor farming practices, overgrazing, excessive irrigation, over drafting (the process of extracting groundwater beyond the safe yield of the aquifer), commercial development and land pollution through industrial waste disposal to arable lands. Land degradation in India is estimated to be occurring on 147 million hectares (m ha) of land, including 94 m ha from water erosion, 16 m ha from acidification, 14 m ha from flooding, 9 m ha from wind erosion, 6 m ha from salinity, and 7 m ha from a combination of factors. Causes of land degradation are both natural and human-induced. Natural causes include earthquakes, tsunamis, droughts, avalanches, landslides, volcanic eruptions, floods, tornadoes, and wildfires. Human-induced degradation results from land clearing and deforestation, inappropriate agricultural practices, improper management of industrial effluents and wastes, over-grazing, careless management of forests, surface mining, urban sprawl, and commercial/industrial development. Social causes of soil degradation in India are land shortage, decline in per capita land availability, economic pressure on land, land tenancy, poverty, and population increase


Today & Tomorrow’s Printers and Publishers

(Bhattacharyya et al., 2015). The already imbalanced consumption ratio of 6.2:4:1 (N: P: K) in 1990-1991 has widened to 7.2:7:1 in 2000-2001 and 5:2:1 in 2009–2010 compared to a target ratio of 4:2:1. As food grain production increased with time, the number of elements deficient in Indian soils increased form one (N) in 1950 to nine (N, P, K, S, B, Cu, Fe, Mn and Zn) in 2005-2006. Although the use of fertilizer has increased several folds, the overall consumption continues to be low in most parts of the country. Widespread Zn deficiency, followed by S, Fe, Cu, Mn and B are common throughout the country. Every year, ~20 mt of the three major nutrients ie., N, P and K are removed by growing crops, but the corresponding addition through inorganic fertilizers and organic manure falls short of this harvest. Loss through soil erosion is another reason for soil fertility depletion, accounting for an annual loss of 8 mt of plant nutrients through 5.3 billion tons of soil loss (Prasad and Biswas, 2000). Intensive agriculture has also led to doubling of irrigated crop land over the past four to five decades (from 19 to 40%). Excess nitrate has leached into ground water due to heavy N fertilizer use. Excessive tillage for land preparation and planting, indiscriminate irrigation and excessive fertilizer applications are the main source of GHG emission from agricultural systems. Burning of crop residues for cooking, heating or simply disposal are the pervasive problem in India which contribute to soil organic matter (SOM) loss. About ~500 mt of crop residues are generated every year and ~125 mt are burnt in the country (NAAS, 2012). Improper crop rotation coupled with lack of proper soil and water conservation measures is important reasons contributing to soil erosion in lands under cultivation. In addition, cultivation of marginal lands on steep slopes, in shallow or sandy soils, with laterite crusts and in arid or semi-arid regions bordering deserts resulted in land degradation. While advancing food and nutritional security, adoption of restorative land use and recommended management practices are important to strengthening numerous ecosystem services such as improving water quality and renewability, increasing below and above-ground biodiversity, enhancing soil resilience to climate change and extreme events, and mitigating climate change by sequestering C in soil and reducing the emission of CO2, CH4 and N2O. Due to growing resource degradation problems worldwide, conservation agriculture (CA) has emerged as an alternative strategy to sustain agricultural production. It is a concept for resource saving agricultural crop production that strives to achieve acceptable profits together with high and sustained production levels while promoting the

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


environmental balance (FAO, 2008). CA is based on principles of enhancing natural biological processes above and below the ground. Intervention such as mechanical soil tillage are reduced to an absolute minimum and use of external inputs such as agrochemicals and nutrients of mineral or organic origin are applied at an optimum level. About 157 m ha is covered under CA worldwide and USA, Brazil, Canada cover most of the area. In India, about ~3 m ha area is under CA in rice –wheat system, mainly in Indo-Gangetic Plains (Sharma and Singh, 2014). Zero till (also called no-till), minimum tillage, Furrow Irrigated Raised Bed (FIRB), laser leveling, incorporation/retention of crop residues etc. are major CA technologies promoted in India. This has been possible mainly due to the development of the new generation machineries like zero till drills, rotary disk drills, happy seeders, laser levelers etc. But all these developments have been mainly in the irrigated belts of Northern India. On the other hand there are meager attempts for developing CA technologies suitable for the low input hill agriculture. Even though some of the indigenous resource conserving technologies are prevalent in the North Eastern Hill Region, they are confined to their place of origin. Increase in population pressure also forcing farmers to go for intensive method of cultivations. In the rainfed hill zones, mechanization is meager mainly due to difficult terrains, small holdings and poor economic condition of the farmers. High rainfall, excessive disturbance to the soil along with faulty agricultural practices are resulting serious land degradation in terms of erosion, nutrient loss etc. Reduced tillage coupled with residue management would reverse the trend of degradation to a great extent. A tonne (t) of rice residue contains 6, 2 and 11 kg NPK, respectively. Crop rotations result in increased SOC content, more so with introduction of leguminous crops. In rice based cropping system, mulch farming (Aulakh et al., 2001), green manuring (Kumar et al., 1999), integrated nutrient management (Duxbury, 2001; Lal et al., 1998) and conservation tillage (Hobbs and Gupta 2003) have been reported to enhance soil carbon stocks. Adoption and spread of no-till (NT) wheat has been a success story in north-western parts of India due to: (i) reduction in cost of production by Rs. 2000-3000 per ha, (ii) Improvement in soil quality, (iii) enhanced C sequestration and buildup in soil organic matter, (iv) reduced incidence of Phalaris minor in wheat, (v) enhanced water- and nutrient-use efficiency, (vi) timely and early sowing date, (vii) reduction in GHG emission (viii) avoiding crop residue burning, loss of nutrient, environmental pollution, reduced serious health hazard, (ix) providing opportunities for crop diversification and intensification etc. (Sharma and Singh, 2014).


Today & Tomorrow’s Printers and Publishers

CA in North Eastern region of India The North Eastern Region (NER) of India, comprises the states of Arunachal Pradesh, Assam, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim and Tripura, lies between 22005’ and 29030’ N latitudes and 87055’ and 970 24’ E longitudes. The region is characterized by diverse agroclimatic and geographical situations. On steep slope, because of continuous removal of topsoil, organic matter status is poor to medium. In this region, around 56% of the area is under low altitude, 33% mid altitude and the rest under high altitude. Traditionally, farmers both at upland terrace and valley land follow mono-cropping practice in rainfed agriculture, where rice is the major crop occupying more than 80% of the cultivated area followed by maize. Farming in rainfed North-East India is complex-diverse-riskprone (CDR) type (Bhatt and Bujarbaruah, 2005). Intensive natural resources mining and continuous degradation of natural resources (soil, water, vegetation) under conventional agriculture practices will not ensure farm productivity and food security for the coming years. In order to keep production system in different land situations sustainable, CA based on minimum/ no-till system is an alternative to conciliate agriculture with its environment and overcome the imposed constraints of the climate change and continuous inputs cost. Resource Conserving Techniques (RCTs) using locally available resources encompasses practices that enhance resources or input-use efficiency and provide immediate, identifiable and demonstrable economic benefits such as reduction in production costs, saving in water, fuel, labour requirements, and timely establishment of crops resulting in improved yields (Ghosh et al., 2010). Even though the region receives high rainfall (>2000 mm), there is severe water scarcity in upland during November to April that makes cultivation of rabi crops difficult in the absence of soil moisture conservation measures. On the other hand, there is excess moisture in low land due to seepage from surrounding hillocks. Cultivation of a second crop of rice is not possible due to early onset of winter and subsequent problem of spikelet sterility especially in high altitudes. In the region, the farmer ’s immediate concern is crop yield improvement, diversity of crops, and enhancement of basic income for their livelihoods. The basic social concept of sustainable management of land is based on balance among the different segments of the society as well as a balance between individual and institutional values. Intensive agriculture and excessive use of external inputs lead to degradation of soil, water and genetic resources. Wide spread soil erosion, nutrient mining,

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


depleting ground water table and eroding biodiversity are the global concern which are threatening the food security and livelihood opportunities of farmers, especially the poor and underprivileged. Globally, about 10 m ha of good quality land is lost annually for agricultural uses due to soil degradation which adversely affects agricultural production and profitability. Therefore, there is urgent need to reverse the trend of natural resource degradation. Land degradation in hill eco-system Hill landscape and physiography are prone to accelerated water runoff, soil erosion, sedimentation, and non-point source pollution. Thus, ecological and soil restoration are critical to improving productivity of agro-ecosystems, eliminating hunger and poverty, and enhancing human wellbeing. Ecological restoration of degraded hill lands would trigger the process of soil/terrestrial C sequestration, improvements in productivity and use efficiency of inputs, mitigation and adaptation of climate change, provisioning of essential ecosystem services, increase in biodiversity by restoration of wildlife habitat, and increase in human wellbeing (Lal, 2015b). Historic land misuse and soil mismanagement of hill agriculture in India and elsewhere have strongly depleted the soil/terrestrial C reserves. Changes in soil microbial processes, especially the increase in microbial activity and species diversity, can accentuate the rate and magnitude of SOC sequestration even with low rate of input of biomass-C (Kallenbach et al., 2015a). Jhum (shifting) cultivation and other extractive practices of hill farming in NER and elsewhere have adversely impacted biodiversity and jeopardized the stability of ecosystems in these fragile environments. Soil loss to the tune of 46 t/ha/year have been reported under shifting cultivated area (Sharma and Prasad, 1995) as against country’s average of 16.4 t/ha/ year (Bhattacharyya et al., 2015). Decline in biodiversity also reduces productivity, environment quality, and human wellbeing. Indeed, biodiversity plays a critical role in ecosystem productivity and ecological stability (Hautier et al., 2015), which must be enhanced. Thus, re-wilding of marginal/depleted hill lands would be an essential pre-requisite to reversing the degradation trends (Lal et al., 2015b). Intensive tillage, residue burning and along the slope cultivation are the major threats to environment and food security. Excessive tillage disrupts soil structure, breaks pore continuity and during heavy rains facilitates dislocation of soil particles and promotes soil and nutrient erosion. Burning of biomass releases carbon monoxide and in-turn CO2 to


Today & Tomorrow’s Printers and Publishers

Fig 1. Concept of restoring degraded hill lands (Adopted from Lal, 2015b with permission)

the atmosphere. It is estimated that about 10 t/ha dry biomass is burnt amounting to burning of about 9 million tones biomass annually in NER (Das et al., 2011). Thus, it is warranted to identify and employ efficient technologies to use scarcer natural resources to attain food security and mitigate impact of climate change. Lal (2015b) proposed a model for restoring hill ecosystems and advancing food security for human wellbeing (Fig 1). Erosion control, nutrient recycling, increase in carbon pool, biomass production and ecosystem stability have been emphasized for restoring degraded hill ecosystems.

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


Concept of conservation agriculture The concept of CA evolved as a response to concerns of sustainability of agriculture globally and has steadily increased worldwide to cover ~ 10% of the world arable land. CA is a resource-saving agricultural production system that aims to achieve production intensification and high yields while enhancing the natural resource base through compliance with three interrelated principles, along with other good production practices of plant nutrition and pest management (Abrol and Sangar, 2006). Reduced tillage, diversified crop rotation, surface cover and water conservation are the principal components of CA with respect to rainfed farming which when followed scientifically lead to better soil health and contributes to yield sustainability (Srinivasa Rao et al., 2015). Reducing tillage intensity and retaining residues are important components of CA but in small holder systems in developing countries where crop residues have alternate uses such as fodder and fuel wood, recycling or external additions of organic matter may be a possible option (Prasad et al., 2016). CA, considered as an alternative strategy world over to sustain agricultural production, is widely reported to reduce soil erosion, enhance infiltration, improve SOC stocks and enhance soil quality, while reducing risks of soil degradation under rainfed conditions (Vlek and Tamene, 2010). However, development of CA systems in rainfed agriculture is at infancy in India due to several reasons. Availability of sufficient amount of crop residues for surface retention is a major issue in rainfed ecosystems as cropping is restricted to a single season and crop residues are used as fodder for the livestock population. The benefits associated with reducing tillage intensity are limited in the absence of retention of crop residues (Derpsch et al., 2014) particularly under rainfed conditions where the soil is exposed without any vegetative cover for up to 9 months a year. The same is true for NER of India, where cropping intensity is about 134% i.e, about 66% land remains fallow after kharif crop. Cultivation on sloping land exacerbates erosion, depletes soil nutrient and C-stock, degrades soil quality and ultimately reduces productivity. Residue burning is another aspect of unsustainable agriculture in the NER. Efficient management of residues can contribute to conservation of soil moisture during dry season and nutrient recycling through microbial decomposition.


Today & Tomorrow’s Printers and Publishers

Table 1. A comparison of conventional tillage and conservation agriculture Issues

Conventional Agriculture (CT)

Conservation Agriculture (CA)


Disturbs the soil and leaves a bare surface

Minimal soil disturbance and soil surface is permanently covered

Cropping system

Monocropping/culture, less efficient rotation

Diversified farming and more efficient rotations

Residue management

Residue burning or removal

Residue retention on the soil surface


Wind and water erosion is maximum

Wind and water erosion is the least

Soil physical health

Very poor

Comparatively good

Soil biological health

Poor biological health owing to frequent disturbance

More diverse and healthy biological properties and populations

Water infiltration

Lowest after soil pores clogged

Better water infiltration

Soil organic matter

Low due to oxidation of organic matter and residue removal

Soil organic carbon build-up


Controls weeds and also causes more weed seeds to germinate

Weeds are a problem especially in the early stages of adoption, but problems are reduced with time and residues can help suppress weed growth

Diesel use and costs

Diesel use high

Diesel use much reduced

Production costs




Operations can be delayed

Timeliness of operations more optimal


Can be lower where planting delayed

Yields same as CT but can be higher if planting done more timely

Source: Hobb et al. (2008); Sharma et al. (2012)

Components of CA The major components of CA includes minimal soil disturbance, maintaining soil cover and crop diversification. Evaluation of various components of CA as described below have shown tremendous potential for enhancing input use efficiency and sustainable farming.

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1

Land leveling

Zero-till systems

Furrow Irrigated Raised Bed (FIRB) planting systems

Crop residue management

Crop diversification

Leaf colour chart


Land leveling: Unevenness of the land surface influences the farming operations, energy use, aeration, crop stand and yield mainly through nutrient-water interactions. The general practices of land leveling used by the farmers in India is either through use of plank drawn by draft animals or by small tractors. Farmers in Indo-Gangetic Plains (IGP) especially in Punjab, Haryana and Uttar Pradesh use iron scrappers/leveling boards drawn by tractors. But, these leveling practices are not so perfect even after best efforts for leveling which results in less input use efficiencies and low yield at the cost of more water and energy. High crop yields depend on optimum seedling emergence, better crop stand and early crop vigor. Laser land leveling is one of the few mechanical inputs in intensively cultivated irrigated agriculture and improves the input use efficiencies. In the plains of North India, laser land leveler is used that level land to a perfection of ± 2 cm from the average elevation. Only by leveling land, the yield can be increased by 10-25%, saves water to the tune of 40%, increase nutrient use efficiency by 15-25% and increases land area by 2 to 6% due to reduction in area required for bunds and channels under conventional systems (Jat et al., 2004). The soil moisture status throughout the field governed by its levelness has great influence not only on farming operations but also on the yield and input use efficiency. The leveling of land for achieving higher resource use efficiency is not a new technique but the way in which it is done is not up to the mark as frequent patches of dikes and ditches stretched over and minimum workable distance are created even with best efforts by conventional leveling practices. Undulated land hampers the seedbed preparation, seed placement, germination and also requires heavy draught for machines, which leads to consumption of more energy and ultimately to more cost of production and low productivity levels (Jat et al., 2005). Zero-till seedling performs better on a well-leveled field compared to unleveled or fairly leveled field due to better seed placement, germination and uniform distribution of irrigation water and plant nutrients. The benefits of precision land leveling using laser equipped


Today & Tomorrow’s Printers and Publishers

drag bucket includes (Jat et al., 2004) – 

Improving crop establishment

Improving uniformity of crop maturity

Approximately 3 (canal irrigated area) to 6% (tube well irrigated area) increase in cultivable area

Has potential to increase water application efficiency by over 50%

Increase in water productivity of crops

Increase in yield of crops (15 to 25%)

Approximately 20-40% saving in irrigation water

Increase in nutrient use efficiency (15 – 25%)

Reduces weed problems and improves weed control efficiency.

Zero till / reduced tillage system: One of the most important principles of CA is minimal soil disturbance. In no-till (NT) or zero till (ZT) system, the seed is placed into the soil by a seed drill without prior land preparation. This technology has been tested and is presently being practiced over 3.0 m ha in India. This technology is more relevant in the higher yielding, more mechanized areas of north western India, where most land preparation is now done with four-wheel tractors. However, in order to extend the technology in Eastern parts of the IGP, drills for small tractors, 2-wheel hand tractors and bullocks have been modified and the drills are made available to the farmers. In India, the burning of non-conventional fuel and resultant emission of greenhouse gases is severe in agriculturally most important region i.e., Indo-Gangetic basin. Rice-wheat is the dominant system of this region wherein conventional method of land preparation/ sowing, not only disturbs the soil environment but also leads to atmospheric pollution. It is estimated that for each liter of diesel fuel consumed 2.6 kg of CO2 is released to the atmosphere. Assuming that 150 litres of fuel is used per hectare per annum for tractor and irrigation purposes in conventional system, it would amount to nearly 400 kg CO2 being emitted per annum per hectare. Hence, in the direction of CA, no-till system has been proved to be the important step in the CA and economic growth. A quantum of work have been done (Gupta et al., 2005) demonstrating the savings on fuel, labour, irrigation water, production cost, energy etc. along with positive effects on soil health and environmental quality benefits of no-till system in India.

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


Bed planting systems: Furrow Irrigated Raised Bed (FIRB) or bed planting is a system in which crops are grown on ridges or beds. The height of the beds is maintained at about 15 to 20 cm and having a width of about 40 to 70 cm depending on the crops. In case of wheat, around 45 cm bed width is maintained and generally three rows having a distance of 15 cm are sown. The major concern of this system is to enhance productivity and save the irrigation water. There is evidence for the greater adoption of this practice in the last decade in other parts of the world like high-yielding, irrigated, wheat growing area of north-western Mexico. Therefore, the bed planting rose from 6% of farmers surveyed in 1981 to 75% in 1994. the use of raised beds for the production of irrigated non-rice crops was pioneered in the heavy clay soils of the rice growing region in Australia in the late 1970s (Maynard, 1991), and for irrigated wheat in the rice-wheat (R-W) areas of the IGP during the 1990s, which was inspired by the success of beds for wheat-maize systems in Mexico (Sayre and Hobbs, 2004). Potential agronomic advantages of beds include improved soil structure due to reduced compaction through controlled traffick, and reduced water logging and timely machinery operations due to better surface drainage. Beds also create the opportunity for mechanical weed control and improved fertilizer placement. In R-W systems in Asia and Australia, permanent beds also provide the opportunity for diversification to water logging sensitive crops not suited to conventional flat layouts, and the ability to respond rapidly to marker opportunities. Various trials across IGP suggests irrigation water savings of 12 to 60% for direct seeded (DSRB) and transplanted rice on beds (TRB) compared to puddled transplanted rice (PTR) (Balasubramanian et al., 2003). However, many studies at North Western IGP showed little effect of rice on beds (TRB or DSRB) on water productivity (about 0.30 to 0.35 g/kg) as the decline in water input was accompanied by a similar decline in yield (Sharma et al., 2002). Crop residue management: Drastic reduction in soil organic matter (SOM) due to limited recycling of organic biomass owing to residue removal and/ or burning is the key contributor to the un-sustainability of agriculture. Burning crop residues due to lack of efficient technologies for in-situ recycling not only leads to loss of considerable amount of NPK and other nutrients but also contributes to global CO2 and N2O budget (Grace et al., 2002). Substantial quantum of (80.12 m t/annum) of crop residues is available for recycling from rice –wheat cropping systems with very good nutrient potential (Pal et al., 2002). Recycling of such a high amount of crop residue into the soil would help in improvement of soil fertility in the


Today & Tomorrow’s Printers and Publishers

IGP. Development of new generation drills (happy seeders, rotary disc drill, double disc drill, punch planter etc) will be the key in the promotion of CA in India. In-situ residue management: Effective management of residues, roots, stubbles, and weed biomass can have beneficial effect on soil fertility through addition of organic matter and plant nutrients, and improvement in soil condition . Rice straw contains organic materials and nutrients such as N (0.5–1.5%), P (0.2–1.0%) and K (0.8–1.0%) (Mongkol and Anan, 2006). It is well documented that the incorporation of organic manure or crop straw into soil improves soil fertility and increases crop yield (Eneji et al., 2001). The residual effect of incorporating rice straw into the soil resulted in significant increase in grain yield after three years of practicing this method (Prasert and Vitaya, 1993). Chutiwat and Direk (1997) reported that incorporating rice straw into soil increased grain yield by 15–18% over burning. Direct dry seeded and un-puddled transplanted rice: Direct seeding has advantages of faster and easier planting, reduced labour and less drudgery with earlier crop maturity by 7-10 days, more efficient water use and high tolerance of water deficit, less methane and often higher profit in areas with assured water supply. Thus, the area under direct seeded rice has been increasing as farmers in Asia see higher productivity and profitability to offset increasing costs and scarcity of farm labour (Balasubramanian and Hill, 2002). Weed control is a major issue in direct seeded rice. Direct seeding of rice using zero till seed drill, rotary till drill, drum seeder as well as broadcasting under various field preparation or puddling options was tried at Directorate of Wheat Research, Karnal research farm. Seeding depth was kept at 2-3 cm while using drill for seeding. For comparison purposes transplanting was also done under conventional puddling as well as under zero till and after field preparation with rotary tiller (Sharma et al., 2003). Direct seedling of rice variety IR 64 was done in the first week of June on the same day when nursery was sown for transplanting. For weed control Sofit @ 1500 ml/ha was applied after four days of direct seeding followed by one weeding at around 35 days after seeding. Among the direct seeding options, the yield recorded was highest where rice was seeded using rotary till drill followed by broadcasting sprouted rice seed after preparation by rotary tillage and lowest when broadcasted under zero till. The mean yield in rotary tillage was significantly higher compared to zero till. Direct drilling by zero till drill

Conservation Agriculture for Advancing Food Security in Changing Climate, Vol. 1


and rotary till drill was at par and as good as transplanting under zero tillage or after field preparation by rotary tillage and was significantly better than broadcasting and drum seeder but statistically at par with other transplanting or seeding options. The yield was marginally higher in conventionally puddle conditions compared to transplanting without tillage. Direct seeding of rice under lowland unpuddled condition at Umiam, Meghalaya gave promising results. Varieties like Shahsarang 1, Krishna Hamsha performed well. This technology can overcome the problem of water supply for rice transplanting during pre-kharif season and thereby save resources. Direct wet seeded rice: In this system sprouted seeds are broadcasted or placed with drum seeder under puddle or unpuddled conditions. Wet direct seeded rice also reduces labour costs and effective herbicides for weed control have helped making this technology more popular. Seed rate in drum seeded rice varies from 50-75 kg/ha whereas, in broadcasting method of seeding 20-30 kg/ha is sufficient. Puddling can be avoided in wet seeded rice without any adverse effect on rice yield. The observations at farmers’ field showed that mortality of sprouted seeds is higher under puddle compared to unpuddled conditions. A field trial on direct seeded rice was conducted with different seed rates varying from 20 to 80 kg/ha. The variety used was IR 64 having a 1000 grain weight of about 26 grams. The yield recorded was almost similar at seed rate of 20 to 80 kg/ha (Sharma et al., 2003). Crop diversification: Crop diversification is important in mitigating the environmental problems arising on account of monoculture. Inclusion of crops like legumes or crops of different habits in rotation and intercropping systems has been found to improve soil heath, reduce weed and pest problems to a great extent. Choice of appropriate cropping systems and management practices helped in minimizing nitrate leaching besides improving N-use efficiency. Legume intercropping in cereals grown with wider row spacing has been reported to reduce citrate leaching. Under mid altitude of Meghalaya, rice + soybean and rice + groundnut (4:2 row ratio) have been found economical. Under lowland condition, after harvest of kharif rice, pea and lentil and toria were found effective under zero tillage condition. Leaf colour chart: Leaf colour is a fairly good indicator of the nitrogen status of plant. Nitrogen use can be optimized by matching its supply to the crop demand as observed through change in the leaf chlorophyll content and leaf colour. The leaf colour chart (LCC) developed by International


Today & Tomorrow’s Printers and Publishers

Rice Research Institute (IRRI), Phillipines can help the farmers. The monitoring of leaf colour using LCC helps in the determination of right time of nitrogen application. Use of LCC is simple, easy and cheap under all situations. The studies indicate that 10 to 15 % nitrogen can be saved using the LCC (Sharma et al., 2008). CA and carbon sequestration Integrating farm-generated organic manure with inorganic fertilizers to increase SOC, and combining crop rotation, residue management and reducing the tillage intensity appears to be the feasible strategy under rainfed conditions (Campbell and Zentner, 1993) particularly for small farmers whose holdings are

Suggest Documents