Maize (Zea mays L.) is one of the important cereal crop in India having the wide adaptability to soil and diverse agroclimatic conditions and under different cropping sequences. It has emerged an important crop for food, nutritional security and farm economy in India and occupies 8.17 million hectares area with an average productivity of about 2.4 t/ ha, and contributing 8.5 % to national food basket.
Presently, in India, maize is mainly used for the preparation of poultry feed and extraction of starch and also provides food, animal feed, fodder and basic raw material for the various industries viz. biofuel, food sweeteners, cosmetics and alcoholic beverages etc. These diversified uses of maize also prompted higher production across the country.
India is the fifth largest producer of maize after the USA, China, Brazil and Mexico in the world contributing 3% of the global production. In India, nearly 75% of maize the production is from Kharif season and remaining 25% during rabi and spring/summer season. Since the maize is primarily grown under rainfed conditions during Kharif season but in rabi, it is grown under assured irrigation.
Maize area, production and productivity in India have seen phenomenal growth over the last five decades and have emerged from being a net importer to levels of self-sufficiency. In the last five decades, India’s maize production has increased from less than 4 million tonnes (1950-51) to 19.73 million tonnes (2008-09) today. This is because of growth in improved production technologies coupled with rising demand for the produce.
2.Major maize-based production systems in India
The shift in traditional crops and cropping sequences to maize-based systems are gaining importance given changing resource base under the current farming scenario. With the development of high yielding varieties and hybrids of maize and efficient resource use production techniques that are competitive with rice and wheat concerning farm profitability and are efficient under the diverse soil, season and climatic conditions have led to the development of several maize-based cropping systems (Table 1& 4).
Furthermore, under the emerging limitations of natural resource base with the existing intensive cropping systems and excessive use of external inputs lead to the degradation of soil, water and genetic resources. Under situations of declining water table and natural resource base degradation and market drove modern agriculture under the peri-urban interface, maize is emerging as an alternative option for crop diversification. In the peri-urban interface, maize-based high-value intercropping systems are also gaining importance due to market-driven farming.
Further, maize has compatibility with several other crops of different growth habit that led to development of various intercropping systems among different maize-based cropping systems, maize-wheat ranks 1st and it is the 3rd most important cropping system after rice-wheat and rice-rice having 1.8 m ha area that contributes about 3% to the food grain production in India. Studies carried out at various soil, and climate conditions under All India Coordinated Research Project on Cropping System revealed that compared to existing cropping systems maize-based cropping systems are a better user of water and available resources at different locations
3.Conservation agriculture (CA) in maize-based cropping systems
Traditionally, maize, wheat and other crops in the maize-based crop sequence are grown either in row geometry or by random broadcasting, mostly after thoroughly tilling the field till proper tilth is obtained for good seedling emergence. The traditional practices of growing these crops have several limitations such as inconvenient input management when sown by broadcasting, improper plant geometry, and uneven plant population resulting in inefficient utilization of space and plant competition leading to low productivity and input use efficiency. But, now evidence of second generation problems that includes declining factor productivity, stagnating crop productivity, declining soil organic matter (SOM) receding ground water table, diminishing farm profitability, environmental pollution etc. started appearing mainly attributed to a monoculture of intensive conventional production systems. At
present, the real challenge in Indian Agriculture is to produce more quality food for the burgeoning population from the same land and water resources, besides sustaining soil health and environmental quality. India alone needs to produce an additional 64 million tonnes of food over the next decade to achieve targeted 294 million tonnes by 2020. Here the important question is where will be the future productivity gain come from? Will germplasm improvement research repeat the progress achieved in the last four decades?
To us, it seems that future growth in productivity in intensively cultivated systems will come increasingly from the adoption of improved natural resource management practices designed to increase the efficiency of inputs in irrigated semi-arid and sub-humid tropics and improving the productivity in rainfed agro-ecosystems. Thus, the major challenge in future for the researchers will be to develop an alternative system that produces more at less cost with low water and energy and improve farm profitability and sustainability.
Incidentally, these are the areas where single cross maize hybrid based technology in combination with improved natural resource management practices viz., conservation agriculture based resource conservation technologies (RCTs) act as a driver in enhancing the crop productivity and farm profitability. This indicates that agriculture systems need a combination of new technologies that are capable of knocking new sources of productivity growth and are of more sustainable. This necessitates paying more attention to issues of sustainability and Conservation Agriculture (CA) in intensive production systems. The efforts by researchers made since mid-1990’s on developing, refining, accelerating and enhancing the adoption of CA technologies in India has brought a “Revolution in tillage techniques”.
Conservation agriculture (CA) aims to achieve sustainable and profitable agriculture and subsequently aims at improved livelihoods of farmers through the application of the three conservation agriculture principles: minimal soil disturbance, permanent soil cover and suitable crop rotations. Conservation Agriculture holds tremendous potential for all sizes of farms and agroecological systems, but its adoption is perhaps most urgently required by small-holder farmers, especially those facing acute shortage of labour. It is a way to combine profitable agricultural production with environmental concerns and sustainability, and it has been proven to work in a variety of agro-ecological zones and farming systems.
The benefits of maintaining crop residue on the soil surface are well documented and include reduced soil loss as a result of water or wind erosion, as well as increased infiltration of water and soil water storage efficiency. Other benefits of conservation tillage (CT) systems include reduced labour, fuel, and machinery wear, improved soil tilth, increased soil organic matter, improved water and air quality, and increased biodiversity/wildlife.
4. Why is Conservation Agriculture needed in Indian Agriculture?
- Due to the intensive production system,
- Excess withdrawal of tubewell water for irrigation,
- Residue removal and burning,
- Degradation of soil structure due to excess puddling in rice,
- Depletion of soil organic matter
- Nutrient imbalance,
- Soil salinity and sodicity,
- Specialization of pest problem due to monoculture
- Small farm sizes with each farm operating as integrating the farming system, and
- In certain situation, where tillage operations caused a delay in sowing and add to the cost of production.
5. Climate change and Conservation Agriculture based technologies
Conservation Agriculture based practices provide an integrated approach aimed at adaptive and mitigation strategies to face the risk of climate change on agriculture. Adaptive strategies include improved use efficiency of water and nutrients; improved ability to cope with extreme events – drought, excess rain period, soil temperature variation, changed pest/disease scenario; opportunity to develop a biologically mediated approach aimed at sustainable productivity enhancement; ensuring timely sowing due to saving of time spent on tillage and opportunities offered for crop intensification in the face of resource constraint. The Conservation Agriculture based mitigative strategies for the impact of climate change on agriculture is enhanced sequestration of carbon through soil and biomass; reduced dependence on chemicals and reduced GHG emissions on account of practices like minimal tillage, crop residue retention, carbon sequestration etc.
Conservation tillage fields act as a sink for CO2 and conservation farming applied on a global scale could provide a major contribution to controlling air pollution in general and global warming in particular. The conservation of resources (land, water, energy) saves the cost of water, energy and protects the environment while leading to improved productivity on a sustainable basis. Targeting the resource-conserving technologies offers newer opportunities for a better livelihood for the small and marginal farmers. Hence, adoption of resource-conserving technologies viz., new cultivars, reduced or minimum pre-planting tillage, soil water management practices is essentially needed to revert the damage done to the natural resources. Resource conservation technologies improve input use efficiency at low cost and preserve the ecological integrity of the crop production system.
In the conventional system involving intensive tillage, there is a gradual decline in soil organic matter through accelerated oxidation and burning of crop residues causing pollution, greenhouse gases emission and loss of valuable plant nutrients. When the crop residues are retained on the soil surface in combination with no tillage, it initiates processes that lead to improved soil quality and overall resource enhancement. Tillage aims to create a soil environment favourable to plant growth. Appropriate tillage practices are those that avoid the degradation of soil properties but maintain crop yields as well as ecosystem stability.
6.Machinery development and Conservation Agriculture
The real success of conservation agriculture in South Asia started with the development of second generation planters included the précised seed metering and furrow opening system in addition to seeding in the loose and sanding residue.
a)Zero-till seed drill:
Seed drill which is conventionally used generally has seed and fertilizer boxes, wide shovel type furrow openers, seed metering device, seed and fertilizer delivery tubes and seed depth control wheels. While zero-till ferti-seed drill has all these components except that the wide furrow openers are replaced with chisel or “inverted T” type openers to place seeds and fertilizers in narrow slits with minimal soil disturbance. To facilitate seeding into loose residues, double disc type furrow openers and star-wheel (dibble) type openers can also be used with the existing zero-till seed-cum-ferti-drill. Farmers are doing planking after seeding to cover seeds planted with the conventional seed drills. Zero-till seed-cum-ferti-drill planted crop does not require planking. In fact, the zero-till performance of rabi season crops improves if seeds are not covered/planked. As the dew factor received in significant amounts which facilitates germination in rabi crops.
b)Double disc coulters:
This is one of the second generation machines having double disc-coulters fitted in place of tynes to place the seed and fertilizer into the loose residues. The problem being faced with this machine is that being lightweight it fails to cut through the loose residues, and the seed and fertilizer are dropped on the top of it, part of which reaches the soil surface. For proper germination after seeding irrigation is required immediately. This machine may efficiently work up to a residue load of about 4 to 5 tonnes/ha.
C)Punch planter/Star wheel:
It works under low residue load of up to 3 tonnes/ha. This machine is suitable for small and marginal farmer due to low cost and easy handling. Farmers also came with innovations of this type of machine now a days to make CA more successful in Andhra Pradesh.
D)Rotary disk drill (RDD):
This machine was developed by Directorate of Wheat Research, is based on the rotary till mechanism. The rotor is a horizontal transverse shaft having six to nine flanges fitted with straight discs for cutting effect similar to the wooden saw while rotating at 220 rpm. The rotary disc drill is mounted on the three-point linkage system and is powered through the power take-off (PTO) shaft of the tractor. The rotating discs cut the residue and simultaneously make a narrow slit into the soil to facilitate placement of seed and fertilizer. This machine can also be used for seeding under conditions of loose residues as well as anchored and residue free conditions. It can be used as a zero till drill, straight blades or discs can be used for minimal soil disturbance. It is newly designed to seed under diverse situations depending upon the presence and condition of crop residues.
E)Turbo happy seeder:
This is a modified, advanced and light weightt version of the PAU-ACIAR developed ‘Happy Seeder’ to plant a crop in presence of loose and or anchored residues. Turbo seeder differs from happy seeder inthe type of the cutting blades, provision for adjustment of the rows, seed metering system and is lighter in weight. This seeder/ planter can be operated with a 35HP tractor unlike the happy seeder which required a double clutch heavier duty tractor.
Turbo seeder has been found to work satisfactorily in combine harvested fields. This machine has been field tested extensively in Punjab, Haryana and other states. This machine chops the residues in a narrow 5-6 cm wide strip in front of the tines, places seed and fertilizer in the slit opened for placement of seed and fertilizer and it is capable of seeding into the loose residue load of up to 8-10 tonnes/ha, distributed uniformly across the field.
F)Combo happy seeder:
It is a compact, light weight, tractor mounted machine with the capability of managing the total loose straw and anchored crop residue in strips just in front of each furrow opener. It consists of two separate units a straw management unit and a sowing unit. This machine cuts, lifts and throws the standing stubble and loose straw and sows in one operational pass of the field while retaining the crop residue as surface mulch in the field. This PTO driven machine can be operated with 40-60 HP tractors and can cover one hectare in 2.5-5 hours.
7. Conservation Agriculture based resource conservation techniques
a)Laser land levelling:
Traditionally levelled farmer’s field have 5- 15 cm undulation in general within the field, which often result in poor seedling germination, seedling mortality due to water logging and uneven initial crop growth. Laser land levelling improves crop establishment by facilitating planters for uniform seeding depths and also even water application across the fields. Laser land levelling also enables the farmer to apply water and nutrient uniformly facilitating a uniform crop stand and maturity through improved nutrient-water interactions. Therefore, laser land-levelling is a pre-requisite technology and rather an entry point for permanent zero tillage or permanent beds through improved water and crop management. It requires initial high investment on equipment cost so the small and marginal farmers can go for the custom hiring of this technology.
Advantages of laser land levelling:
- Reduces weed problems and improves weed control efficiency
- Improved efficiency of applied fertiliser, herbicides
- Approximately 35-45 % saving in irrigation water
- Reduction in salinity problems
- Uniformed crop maturity
- Improved crop establishment
- Approximately 4-5 % increase in cultivable area
- Easy farm operation due to uniform tilth
The no-till system is a specialized component technology for conservation tillage consisting of a single-tractor operation by using specially designed seed cum fertilizer drill without any field operation due to which the soil and the surface residues are minimally disturbed. The surface residues of such a system are of critical importance for soil and water conservation. Weed control is achieved with herbicides or in some cases with crop rotation. No-tillage systems eliminate all pre-planting mechanical seedbed preparation except for the opening of a narrow (2-3 cm wide) strip or small hole in the ground for seed placement to ensure adequate seed/soil contact.
In bed planting 67 cm wide beds (37 cm ridge and 30 cm furrow) are prepared with the help of bed planter. Bed planter with incline plate seed mattering system can precisely place the maize seed at required depth 3-4 cm. After preparing the fresh beds during the first year, these can keep as permanent beds for the subsequent year with keeping crop residue and reshape if required after harvest of the crop. On permanent beds punch planter can be used to plant maize. One line of maize on each bed is desirable when a sole crop of maize is planted keeping seed to seed spacing at 20 cm. Optimum plant density (30000-35000/acre) should be maintained to tap potentials of hybrids.
Zero tillage or permanent bed for maize has several advantages such as prevent delay in sowing, requires low fuel and labour costs, requires little draft power, most suitable for coarse soils, improves soil health and quality, reduce erosion and conserve soil moisture with higher water use efficiency (15-20%) and yield enhancement. Sometimes temporary water lodged conditions affects the growth of the maize crop.
In bed planting that temporary water lodged conditions can be avoided by draining out excess water in furrows and better infiltration and aeration than conventional till (CT) condition. It was observed that standing water remains for a longer time in CT due surface crust formation or soil compaction while in ZT there is more infiltration rate due to natural soil aggregation which helps in avoiding anaerobic conditions due to water lodging. Zero till or permanent beds have better availability of water for maize especially in residue retained conditions.
Permanent beds conserve moisture during prolong dry spell in water scarcity areas for the longer availability of moisture to sustain plant life and act as a drainage channel in high rain fall/waterlogged areas and provides a better microclimate for plant growth and root development. Following prerequisites should be kept in mind during making permanent beds and planting on it:
- Prepare ridges in East-West direction
- Sowing on the side of the ridge
- Row to row (60-75 cm) plant to plant (20 cm)
- Maintain proper plant spacing: for easy movement in field, rouging and removal of tassels
The use of live mulch and crop residue retention on soil surface using special mulch tillage techniques or practices is an important component of Conservation Agriculture. In situ mulch formed by the residue of a dead or chemically killed cover crop left in place is becoming an integral component of mulch tillage techniques which provides a favourable microclimate for the crop growth and development and avoids extremes. Evaporation loss from the maize crop field can be arrested by covering the soil with organic farm waste like straw or retention of crop residues. This improves water economy by 10-20 %. Therefore, it is viable technology under moisture stress condition. Important crops suitable for mulching in maize are Sesbania, Sunhemp, Green gram, Black gram, etc.
8)The advantages of mulching in Conservation Agriculture are as follows:
- Reducing soil erosion and conserve moisture
- Control weed growth
- The saving of water particularly in arid zones
- The yield of crops may not necessarily be substantially increased directly by usage of mulching, but more land can be cultivated with the available amount of water, and thus overall cultivation of crops can be increased.
- Less salt accumulation on soil surface
- Maintain/moderate soil temperature
- Increase water use efficiency
9)Conservation Agriculture and nutrient management
On a large-scale, N:P:K ratio of 4: 2: 1 has come to known as an ideal ratio, and a deviation in NPK consumption pattern, would suggest imbalanced fertilizers use pattern, greater the departure, more the imbalance. This is not entirely true as there is hardly any basis for the suggested single valued ideal N:P:K ratio. The ratio will be further widening with a mismatch in the demand and supply of major nutrients across the country. The NPK ratio is likely to vary with crops, cropping systems, crop management practices, soils and their reactions. It appears that there is a need to work out new NPK ratios for fertilizer allocations for different zones/regions of the country.
In the demand and supply of fertilizer nutrients, use of organics in agriculture seems inevitable particularly for correcting the N: K imbalances. From plant nutrition point of view, the importance of the concept of balanced fertilizer use lies in adjusting the level of fertilizer use, taking into account available soil nutrients, crops requirement for targeted production levels under specific soil-water-crop management practices. New information seems to strengthen our understanding that Conservation Agriculture has a distinct influence on soil quality and nutrient dynamics as compared with the traditional agriculture based on intensively tilled systems.
The current nutrient prescriptions are (i) age old, (ii) area general- not site-specific (iii) designed for the component crops of the cropping system and (iv) better suited to tilled agriculture. Therefore, the focus should be “feed the soil and let the soil feed the plant”. The key elements of Conservation Agriculture have a direct and indirect bearing on the nutrient availability/supplying capacity of soil which are described as below
a)Minimum disturbance of optimum porous soil architecture
- Optimum proportions of respiration gases in the rooting-zone
- Moderates organic-matter oxidation
- Porosity to water movement, retention and release at all scales
- Limits re-exposure of weed seeds and their germination
b)A permanent covering of sufficient organic matter over the soil surface
- Buffering against the severe impact of solar radiation and rainfall
- A substrate for soil organisms’ activity
- Raised cation-exchange capacity for nutrient capture, retention and slow-release;
- Smothering of weeds
c)Cropping sequences and rotations which include legumes
- Minimal rated of the build-up of populations of pest species, through life cycle disruption
- Biological N-fixation in appropriate conditions, limiting external costs
- Prolonged slow-release of such N from complex organic molecules derived from soil organisms
- Range of species, for direct harvest and fodder
- Soil improvement by organic-matter addition at all depths reached
The important point that emerges from studies in the USA is the accumulation of soil organic matter (SOM), phosphorus and even potassium in 0-10 cm surface soil layer. Accumulation of SOM is advantageous but calls for heavier doses of fertilizer N. Accumulation of P in soil surface may not be of much use to the crops in the succeeding years, and it may reduce the availability of surface applied Zn and other micronutrients. In-depth, studies are therefore needed on nutrient management in ZT drilled crops. It is also advisable to apply a higher basal dose of N, i.e. 40 to 45% of total recommended for the better crop under Conservation Agriculture practices due to initial immobilization of applied N in residue decomposition process.
There are several questions about nutrient management in permanent bed planted crops. When nutrients are applied uniformly before the beds are made, some amounts of nutrients are left in furrows and can remain unutilised. When applied on the beds, the nutrients will remain on the surface, and there could be a problem of reduced availability, especially for less mobile nutrients such as phosphorus. Over the years accumulation of phosphorus in surface soil layer may reduce the availability of other nutrients such as Zn. If applied in furrows, a part of nutrients such as nitrogen can be lost by leaching (Prasad, 2011).
It is only prudent that new fertilizer recommendations should be able to mimic the significant effect of residue retention vis-a-vis incorporation of organics having differential soil moisture and thermal regimes. Therefore, the paradigm shift from tilled to no-till Conservation Agriculture systems require a serious thrust on nutrient management research to improve soil and crop productivity and environmental quality. Carefully planned experiments are needed to develop the nutrient (primary, secondary and micro) management practices for different CA-based technologies in various maize-based cropping systems in India.
10.)Conservation Agriculture and weed management in maize
a)Weed flora of maize-based cropping systems:
In general, weed flora varied between the two nearest fields due to differentiated management practices as well as cropping and herbicide use history. Cyprus rotundus, Bracharia reptans, Dactyloctynium aegyptium, Digera arvensis Digitaria ciliaris, Cucumis spp are the dominant weed flora of maize during the rainy season (Table 1). The weed pressure during the winter season is comparatively less than that appears during the rainy season, the major winter season maize weeds are Cyprus rotundus, Cannabis sativa, Anagallis arvensis and Chenopodium album.
Weeds cause huge yield losses in maize, especially during rainy session. Farmers use hand weeding which becomes difficult due to rains, wet soils and bright sun, moreover, manual weeding effective only for a short period due to favourable environments and requires repeated weeding.
Labour shortage in peak transplanting season delay weeding operation, increasing labour cost and escalating the cost of production the other issues in manual weeding. Farmers need effective and economical alternative weed management strategies.
B)Stale seed bed for weed management in Conservation Agriculture:
Stale seed bed with pre-plant herbicides is one of the important technique to control perennial and annual weeds in maize, and in particular in zero tillage. Application of pre-sowing irrigation facilitates weeds to germinate that can be killed by use of non-selective herbicides. If the germinated weeds are annual weeds, then we can apply either Paraquat or Glyphosate @ 1000 g a.i./ha. In a case of perennial weeds needs to apply glyphosate @ 1000g a.i. / ha . Tank mixture of glyphosate and 2,4-D is a better strategy to control troublesome weed, i.e. Cyperus rotundus. It is advised that use clean water for Glyphosate spray @ 150L/ha and use multi-nozzle boom for better efficacy
c) Pre-emergence weed control in Conservation Agriculture:
In the pre-emergence weed management strategy, by killing germinating weeds, can avoid crop-weed competition during early growth stages. Tank mix application of Atrazine (1000 g a.i./ha), Pendimethalin (1000g a.i. /ha), Atrazine +Pendamethalin (500 g a.i. each/ha) or Alachlor + Atrazine (1250g+ 375g a.i./ha) found effective in controlling annual weeds in summer maize.
d) Post-emergence weed management in CA:
There are limited options for post-emergence weed control in maize due to unavailability of selective herbicides. Atrazine @ 1000 g a.i./ha at 20-30 DAS selective herbicide for maize. As directed spray of Gramoxone in between the row of maize by using covering material (hood) can help in managing annual weeds. Simultaneous planting of mung bean as over crop on either side of maize row on beds appeared effective in controlling complex weed flora.
11.)Conservation Agriculture and crop diversification
Intercropping offers potential advantages for increasing sustainability in crop production under various maize-based cropping systems. Intercropping of short duration grain legume/flower/vegetable crops can be done successfully with long duration and widely sowed maize crop which largely covers initial ground cover and suppresses the emerging weeds. However, intercropping can increase competition between crops and weeds. Maize-legume intercropping led to a higher soil canopy cover (leaf area index) than sole crops.
Thus, in maize-legume intercrops, the decrease in available light for weeds led to a reduction of weed density and dry matter, compared to sole crops. Though maize yield under intercropping is not less than that of the sole maize, rather the intercrop yield is a bonus to farmers. This practice is particularly desirable under delayed sowing, following by late harvest. Due to its erect growth habits and growth period, it suited as inter-crop with many other crops having different growth habit and growing duration. The prominent maize-based inter-crops in India
- Directorate of Maize Research