In this article we will discuss about the irrigated and rainfed cropping systems of India.
A system consists of several components which are closely related and interacting among them. In agriculture, management practices are usually designed for individual crops. On the other hand, farmers cultivate different crops in different seasons according to their suitability to different seasons, domestic needs and profitability. It is, therefore, production technology or management practices should be designed while keeping in view all the crops grown in a year or more than one year (if any sequence or rotation extends beyond one year).
Such a package of management practices for all the crops leads to efficient use of costly inputs and reduction of production cost. For example, residual effects of manures and fertilizers applied and nitrogen fixed by legumes can substantially bring down the cost of crop production, if all the crops are taken in to consideration instead of individual crops.
1. Irrigated Cropping Systems:
Major Cropping Systems of India:
India is a vast and diverse country. Different types of soils and climates are being found here, therefore, different types of crops are grown in different seasons here. Any crop or cropping system is mainly affected by the soil, climate and resources available over there. Apart from these factors, the availability of irrigation or moisture, requirements of farmer, profitability, capital and labour etc. are the other factors which affect the crops and system of growing of them.
Cropping systems vary widely from the simplest system of two crops a year in sequence to complex intercropping with many crops. Multiple crop lands can be broadly grouped in to lowlands, irrigated uplands and rain fed uplands.
Rice-Rice-Rice:
This is the most prevalent cropping system of South India. This cropping system is being adopted in the irrigated and lowland conditions. This cropping system is in vogue in the states of Kerala, Tamil Nadu & Andhra Pradesh. This is being adopted in such areas of these states where irrigation water or rain fall is available at least for 9 to 10 months period.
In this cropping system, rice is being sown or transplanted in the month of June in Kharif season which is harvested in the month of October. By the middle of the October, Rabi rice is sown/transplanted on the same field. This second crop of rice is matured by the mid-February. During the first week of March, the summer rice is sown or transplanted in the same fields which are harvested by the middle of the June.
There is huge requirement of water in this cropping system. On an average, more than 200 mm water availability per month either from irrigation or rain fall is required up to 9-10 months to adopt this cropping system. As the same crop is being grown continuously and the fields remain waterlogged, there are negative effects of this cropping system on the soil health.
Rice-Rice-Upland Crop:
This cropping system is also prevalent in South India. This system is being adopted in the lowland irrigated soils. This is adopted in such areas of South Indian states where irrigation or rain water is available at least for 6-8 months in the year. In this cropping system, rice is being grown in Kharif and Rabi seasons, whereas, any upland crop; like ground nut or any legume of shorter duration is grown during summer season.
From soil health point of view, this cropping system is better than rice- rice- rice cropping system, because legume crops are incorporated in this system and fields are not always saturated/waterlogged. If the availability of water is somewhat limited, then this cropping system can be taken in the form of ‘upland crop (legume)-rice-upland crop’. It is important and essential to have the short duration rice varieties in this cropping system. If the availability of water is only for 4-5 months, then it is possible to grow the rice crop only.
Cultivation of black gram and green gram as a relay crop with paddy (post-rice) is a unique in the coastal areas of Andhra Pradesh as winter season crop in rice fallows (post-rice cropping pattern). Winters being mild, black gram and green gram could be grown after Kharif season rice in peninsular India, covering Andhra Pradesh, Tamil Nadu, Odisha, Maharashtra, Chhattisgarh and parts of Madhya Pradesh. However, the sowing time of pulse crops under rice fallows varies from November to March depending upon the rice harvest in different states.
Cultivation of pulses in rice fallows involves sowing of pulse seeds by broadcasting in the standing rice crop (relay cropping), 2-3 days before its harvest. The crop survives entirely on the residual moisture and fertility. This system, however, does not allow agronomic manipulation like; tillage, weeding, fertilizer application etc. Development of powdery mildew resistant variety LBG 17 has doubled the productivity in farmers’ field from 10 q/ha to 15 q/ha.
However, this variety has been found susceptible to wilt. In 1992, a new high yielding wilt resistant variety Prabhava (LBG 402) was released for cultivation. Under this system, maintenance of optimum plant population, planting time, duration of rice crop, irrigation and fertilizer application are the important factors which decide the performance of the system.
This system has four major components as follows:
i. Improved cultivars
ii. Improved planting geometry
iii. Improved packages of practices
iv. Management of diseases, insects and weeds
This cropping system is adopted in rain fed upland, midland and lowland soils. This cropping system is in prevalence in all the rice growing states of India where irrigation resources are not available and moisture is available only for 4-5 months period. In this system rice is being cultivated in Kharif season only.
After the harvest of rice crop in the months of October or November, fields remain fallow. In this cropping system, the duration of rice varieties are chosen according to the availability of water. By the creation of irrigation facilities in such areas, different crops can be grown in these rice fallows.
In this rice-based cropping system, rice is being grown in the Kharif, whereas, different pulses, oilseeds or cereals are grown during Rabi season. This cropping system is adopted in the rain fed upland and midland soils where mild cool temperatures prevail during the Rabi season. This system is in vogue in the Southern Indian states.
Among pulses; black gram or green gram are cultivated after the harvest of Kharif rice. Apart from these crops, soybean, sunflower, groundnut and sesame are also cultivated. In some areas, different cereal crops such as maize, sorghum, pearl millet, finger millet etc. can also be included in the system in addition to pulses & oilseed crops.
Cotton or different vegetables are planted after the rice harvest. As there are mild cool season during winters in Southern Indian states, therefore, the growth & development of these crops are not affected negatively. As compared to the other crops, inclusion of legumes in the cropping system is better for the restoration of soil fertility.
Irrigated upland soils where good cool winters prevail; this type of cropping system is being adopted. This cropping system is mainly practiced in the states/regions of central and western India. In certain regions of western Indian states, wheat is cultivated even after the harvest of cotton.
In rice-wheat cropping system, rice gets harvested by November month and wheat is being sown during November or December which is harvested in the month of April. In some of the regions; barley, mustard, gram or potato are cultivated in place of wheat.
Under irrigated conditions of Punjab, Haryana, western Uttar Pradesh, Maharashtra, Rajasthan and Gujarat, cultivation of gram after cotton holds good promise. The cotton, which is generally harvested up to end of November, may be followed by gram. Growing gram helps in restoring the soil fertility. In this cropping system, cotton is very exhaustive crop and removes fairly good amounts of nutrients.
The states of Northern India where good cool season prevails during winters, this cropping system is being followed in irrigated uplands. In this cropping system, maize is sown in the month of June and is ready to harvest in September. Before harvesting the maize, potato or mustard or vegetables are sown or transplanted in between the maize rows. These crops are being sown/planted in standing maize crop field under relay cropping system.
These crops are harvested during the month of December. After preparing the field, wheat is sown by the first week of January. Thus, sowing of wheat in this system is possible about two months later than the normal wheat sowing. As there are good cool winters in the region and it lasts up to the month of March, therefore, sufficient time is available for the growth & development of the wheat crop. This late sown wheat crop is harvested by the end of April.
After the harvest of wheat crop, green gram or fodder crops like; sorghum or maize are sown in these field during the month of May. These crops get harvested by the second fortnight of June. Thus, in this cropping system of Maize-Potato/Mustard-Late wheat-Green gram/Fodder crops, four crops are grown with 400% cropping intensity in a year.
In this cropping system, maize and potato, both are heavy feeders of plant nutrients, thus, there are possibilities of detrimental effects on the status of soil fertility. However, inclusion of green gram in the system is helpful in the re-establishment of the soil fertility.
Continuous cropping of cereals (rice-wheat) has led to many problems like; soil sodicity/ salinity, lowering of underground water table (in Punjab, Haryana and Western Uttar Pradesh), depletion in organic matter content of the soil and soil sickness.
Gram has been identified as one of the alternate crops which can replenish the degraded soil fertility and improves it physical properties. Traditionally, gram has been cultivated under upland rain fed conditions. However, with the release of gram varieties like; KPG 59. PBG 1, BG 372 etc. which are suitable for late sowing conditions, the cultivation of gram after rice under late sown conditions has become a profitable preposition.
A non-lodging type variety, DCP 92-3 was released which fits equally good under high input regime of some of the most productive system. Rice-Gram is also spreading under command areas where the irrigation water is often limiting at tail ends during post-monsoon period. The selection of suitable varieties of rice and gram, their planting time, tillage management and efficient use of applied resources are the key factors to decide the productivity and profitability of the system.
The introduction of short duration (140-160 days), high yielding varieties of pigeon pea have paved the way for double cropping and the introduction of pigeon pea in non-traditional areas. Pigeon pea-wheat sequential cropping has spread widely in irrigated areas of northern and central India.
The system is very much popular in the states of Punjab, Haryana, parts of Rajasthan, Gujarat, Uttar Pradesh and Madhya Pradesh, where irrigation facility exists. Generally, wheat follows early pigeon pea. Pigeon pea is often grown at a dense plant population (10-15 plants/m2) as a sole crop. However, in some areas short growing legumes like; green gram, black gram and cow pea are intercropped with pigeon pea.
The first ever shorter duration pigeon pea variety T 21 was released in 1974 for cultivation which spread rapidly in northern India as could be double cropped with wheat and also escape from frost which causes substantial yield loss to long duration pigeon pea. However, it was observed that, t 21 delayed the wheat sowing.
Later on, short duration varieties (140- 150 days) such as UPAS 120, Pusa Ageti, Pusa 74, Pusa 84, Manak, AL 15, ICPL 151 etc. were developed which allow timely sowing of wheat. Results of multi-location trials indicated that, pigeon pea-wheat sequential cropping was highly profitable in northern Indian conditions. The productivity of pigeon pea ranged from 15-20 q/ha. Intercropping green gram or black gram with pigeon pea further increased the monetary return.
Sowing time and selection of appropriate variety of pigeon pea are the important factors that decide the total productivity of the system. The ideal planting time of pigeon pea is early June. A variety maturing by November 15 was found ideal for double cropping with wheat. The pigeon pea variety UPAS 120, AL. 15 and Manak are considered ideal for Uttar Pradesh, Punjab & Haryana.
II. Rainfed Cropping Systems:
This is an intercropping system which is being adopted in rain fed upland soils. This cropping system is in prevalence in all semi-arid regions of the country. As the average annual rain fall in these regions is less and also the water holding capacity of upland soils is lower, hence, it is not possible to take double cropping under sequential cropping system in rain fed conditions.
Sorghum + pigeon pea are grown together in these areas during Kharif season. Sorghum is harvested in the month of October. After the harvest of sorghum crop, more space is available to pigeon pea for its further growth & development. There is shortage of moisture on the soil surface, however, due to its deep & extensive root system, pigeon pea is capable in absorption of sufficient soil moisture.
By the end of December, the pigeon pea crop is harvested, whereas, the long duration pigeon pea varieties mature up to the month of February. The regions which are prone to frost injury should be sown with the short duration varieties which should be matured within the month of December; otherwise there shall be all possibilities of frost injuries.
Apart from the intercropping of sorghum + pigeon pea in these regions, foxtail millet + pigeon pea intercropping is also practiced in the states of Southern India. The farming practiced in these regions is of subsistence type instead of commercial one.
The major objective of intercropping in these regions is to reduce the risk under the situations of complete crop failures. Intercropping also helps the farmers in obtaining the additional income. Various crops are being grown under intercropping system in different semi-arid regions.
This cropping system is being adopted in the heavy rain fed soils. As these soils are finely textured black soils which are extremely sticky in nature, hence, no tillage operation is possible during rainy season. This cropping system is practiced in the areas of erratic rainfall, hence, the fields are left fallow in rainy season and sorghum is grown in Rabi season on stored soil moisture. According to suitability of the region; gram, sunflower, wheat or coriander crops are grown in place of sorghum crop.
This cropping system is followed in the rain fed heavy soils of central India. The soybean in this cropping system is sown immediately after the onset of monsoon. In some areas of this region, the soybean is intercropped with the maize. Both the crops are harvested by the middle of October month and after preparing the fields, rain fed wheat is sown by the end of October.
The success of this cropping system depends on the timely harvesting of soybean crop to enable the field to be prepared immediately and wheat could be sown in stored soil moisture. For this purpose, early maturing soybean varieties should be chosen. An early maturing soybean variety, JS 95-03 is in vogue under this cropping system in central India.
Other Rain Fed Cropping Systems:
Different types of rain fed cropping systems are adopted in different regions of Indian states.
Intercropping system is being adopted in all the semi-arid regions of the country where there is less rainfall and the nature of rainfall is erratic. Only Kharif crop is possible in such areas. Intercropping of sorghum and minor millet crops are taken in these areas.
Minor millet crops like; Paspalum millet, little millet, finger millet, foxtail millet etc. or sorghum are intercropped with the soybean, groundnut or green gram or cow pea during Kharif season. As there is shortage of moisture in Rabi, hence, fields are left fallow.
In the eastern India where soils are medium textured; rain fed maize, rice or finger millets are grown during Kharif season. After the harvest of these crops; linseed, gram, sunflower, wheat, horse gram, mustard, pigeon pea or sweet potato are cultivated in residual moisture during Rabi season.
Rain fed crops is grown on the heavy soils of Deccan Plateau. Green gram is cultivated in Kharif, whereas, sorghum is cultivated in Rabi on conserved moisture. Intercropping system is practiced in heavy black soils of central India and Deccan Plateau. Maize or sorghum is intercropped with pigeon pea in these areas. A double cropping system is also there which is being adopted in the Deccan Plateau.
In this system; maize or sorghum is grown during Kharif season and after the harvest of these crops in the month of October; gram, chili, safflower, pigeon pea or again sorghum is cultivated under conserved moisture. As heavy black soils are found in these areas whose water holding capacity is high, hence, crops can easily be grown on conserved moisture during Rabi season.
Agronomic Management of Cropping Systems:
There are different types of cropping systems. Cropping systems have been grouped in to two major groups viz. irrigated cropping systems and rain fed cropping systems. These both types of cropping systems are adopted in different agro climatic regions at different parts of the country. Owing to the cultivation of crops at different situations, their requirements for agronomic practices are also different. Cultivation practices need to execute at different times and in different manners while managing a cropping system.
In view of these, the management of irrigated and rain fed cropping systems are given below:
Agronomic Management of Irrigated Cropping Systems:
Tillage:
It is essential to sow the succeeding crop in time after the harvest of preceding crop under intensive cropping system, otherwise there are every chances of late sowing of succeeding crop in sequence. Suitable tillage operations are required for sowing the crop seeds and their establishment. Establishing crops after cereals is somewhat difficult without adequate land preparation due to large quantities of residues left behind by the cereals.
The problem is much more complicated after lowland rice crop. Thorough land preparation requires long time which limits multiple cropping systems. No till or minimum tillage methods which have become easy and effective to practice with the introduction of modern herbicides are suggested to reduce the time between two crops.
Different techniques may have to be adopted for different crops that follow rice. Pulse crops can be established on heavy soils by broadcasting presoaked seeds 7-10 days before rice harvest. Crops such as maize and cotton requiring low population can be dibbled by hand.
Sorghum and large seeded legumes can be drilled. Depending on the soil conditions and time available for sowing/planting the second crop, appropriate tillage systems should be followed in intensive multiple cropping systems.
For obtaining the more production under intensive cropping systems, the varieties to be selected should be of high yielding, early maturing, responsive to fertilizers and irrigation. If the crop varieties are not sensitive to temperature and light, they can easily be accommodated in the cropping system. Such types of crop varieties are available now-a-days, hence, two or more crops can be easily grown in a year on the same piece of land provided irrigation facilities are available.
Nutrient elements should be judiciously used under multiple cropping systems. The residual effect of the fertilizers applied to preceding crops should be taken in to consideration while using the fertilizers in the succeeding crop.
Nitrogen fertilizers, generally produce little residual effect, however, continuous application of even moderate doses of phosphorus builds up significant residual phosphorus. Considering the residual phosphorus in mind, one should reduce the quantity of phosphatic fertilizers from its recommended dose.
In intensive cropping system, two or three crops are grown in a year, hence, more quantities of fertilizers are required as compared to the cultivation of a single crop, but crop- wise fertilizers are not applied in this system because the residual effects of previous crops are also taken in to consideration.
The crop-wise recommended fertilizers should only be applied to those crops which are responsive to given nutrients; other crops may be grown on residual nutrients only. Based on this concept, all the primary nutrients viz. nitrogen, phosphorus and potash should be given to the cereal crops. On the other hand, phosphorus and sulfur should be essentially given to the oilseeds and pulse crops. Potash must be given to tuber crops and zinc to the Kharif rice.
In multiple cropping systems, the availability of water plays an important role in the determining the cropping system. If irrigation or rain water is available for 9-10 months in a year, the three rice crops (rice-rice-rice) can be taken in the southern Indian situations.
On the other hand, if irrigation or rain water is available only for 6-8 months in a year, then two crops of rice and one pulse or oilseed crops (rice-rice-upland crop) can be easily taken. Only Kharif rice crop is possible if the water is available only for 4-5 months in a year and the fields are kept fallow in Rabi and summer season.
Along with the irrigation facilities, the provisions of appropriate drainage system are also very important in any cropping system. There are possibilities of degradation of soil health if proper drainage is lacking in the field. As such method of irrigation and irrigation schedules are not different from that of only one crop in a year/season.
Under multiple cropping systems, planning of weed management strategies should not be made while keeping a particular crop in mind, however, the planning should be based on the whole cropping system. It is becomes more importance while using chemical weed control measures, because a chemical used in one crop in the cropping system and its residual effect in the succeeding crop may impair the germination, growth and development of the crop.
The herbicides should be chosen according to the weed species coming in the crops. There is less infestation of weeds in the crops to be grown in sequence after lowland paddy. Similarly, due to the suppressive effect of pulses over weeds, there is lesser weed infestation in the crops grown in sequence.
Agronomic Management of Rain fed Cropping Systems:
The management of rain fed cropping systems is different from irrigated cropping systems. There is no shortage of moisture in irrigated cropping systems; however, the moisture is often deficient in rain fed cropping systems. Assuming this moisture as the premier factor, the selection of rain fed cropping system, their execution and management are done accordingly.
Agronomy of rain fed cropping systems includes all practices controlled by the farmer that contribute to the productivity of crops. Many management decisions are influenced by climate, inherent soil properties and socio-economic constraints. Each decision on crop and cultivar, land preparation, fertilizers and other agronomic practices will have impact on other factors as well.
The climate of rain fed areas is not much suitable so far as the production of crops are concerned. The soils of the rain fed areas are not good and their inherent fertility status is also poor. Rain fed areas is dominated by small and marginal farmers and their land holding is also small along with their poor socio-economic conditions.
All these factors affect the management strategies adopted in rain fed farming systems. Intercropping is the major cropping system in rain fed agriculture, although rationing is practiced under unfavourable rainfall during the season. The details of agronomic managements related to rain fed cropping systems are as under.
Selection of Crops and their Varieties:
There are different problems under rain fed situations like; shortage of moisture, unsuitable and less productive soils and adverse climatic conditions etc. Keeping all these in mind, the crops and their varieties should be chosen. The crops & their varieties should be chosen on the basis of the characteristics like; crop duration, plant morphology, rooting pattern, stress resistance, effect of planting geometry, tolerance to insects and diseases and stability of production etc.
The reason behind the selection of crop and their varieties based on above characteristics is that, the limited resources available under rain fed situations could be fully utilized. Intercropping & mixed cropping are generally practiced under rain fed situations whose primary objective is to reduce the risk of complete crop failures and to fetch the additional income from the subsidiary crops.
Time of Sowing:
The nature of rainfall in rain fed area is very erratic. Sometimes, there is timely onset of monsoon, whereas, sometimes it is late. There may be early withdrawal of monsoon or there may be situation of drought in between the cropping season. There is effect of all these situations in the sowing time, crop establishment and growth & developments and ultimately on the yield of crops.
For timely sowing of rain fed crops during Kharif season, the fields should be ready in advance in summer season itself. As soon as the monsoon is set, crops should be sown immediately. There are two advantages of timely sowing of crops; one, full crop season is available for the growth & development of the crops and second, if crops have been sown in time, their harvesting would also be done in time and thus, next crop in Rabi season under sequential cropping will also be sown in time.
As there is limited moisture availability under rain fed situations, hence, for maximum utilization of this limited moisture, the appropriate plant population is essential. If there is dense population, there may be competition for limited moisture among the crop plants itself or among the different plant species (in intercropping system).
Under such situations, the dominant crop will suppress the dominated crop, resulting in to retardation of growth and development of dominated crop and finally the reduction in crop yields. It is, therefore, care should be taken while choosing the crops that, there should not be any competition among component crops. The rooting pattern of component crops should be taken in to consideration for this purpose.
There is no considerable yield reduction in cereal crops if their population is reduced to a certain extent. These characteristics of the cereal crops provide an opportunity of accommodating more plant population of the component crops which are having the better yield capabilities under intercropping system.
The requirement of component crops is determined by the associated species and the temporal difference between the two crops. In systems where temporal difference is wide (sorghum + pigeon pea, groundnut + pigeon pea), both the component crops can be planted at 100 per cent of the sole optimum population.
On the other hand, the system with closely maturing crops (cereals + legume, ground nut + sunflower) may not require additive population, though the total population of the both the crops may be higher than for either of the sole crops. In general, replacement series (where a proportion of one crop is substituted for a portion of other) is followed for simultaneous planting of component crops and less frequently an additive series (where sole crops densities of two or more crops are planted).
The fertilizer need of a system may be increased, unaltered or reduced, compared to those of sole crops, depending on the component crops involved. If two cereal crops are involved in the intercropping system, then their total fertilizer requirement shall be higher than their sole stands, because both the crops are responsive to the similar nutrients.
Similarly, if both the component crops in intercropping system are legumes, then their phosphorus requirement will be higher than their pure stands. If the cereal crops are intercropped in between the rows of legumes; their nitrogen requirement shall be reduced, because a part of fixed nitrogen is made available to the cereal crops.
Generally, there is no need to apply additional amount of nitrogen if cereals + legumes or legume + legume type intercropping systems are adopted. However, it is essential to apply additional amounts of phosphorus and potash in all intercropping systems.
In the intercropping system of cereals + legume crops, the application method for nitrogen is important. Nitrogen should be given to the cereal crops just adjacent to their rows i.e. as far as possible from the legume crops’ row. If nitrogen is given adjacent to the rows of legume crops, then the process of nitrogen fixation is adversely affected.
If both the component crops require the same nutrient, as with nitrogen when both the component crops are cereals and phosphorus in cereal and legume systems, the nutrient can be applied in one application to both.
There is less infestation of weeds under intercropping system, compared to the cultivation of pure crops, because there is full utilization of limited resources available and hence, weeds do not get much opportunity for their establishment. In such intercropping systems, there are limited possibilities of chemical weed control, because the crops with different nature & characteristics are included in the intercropping systems, hence, an alternative approach of cultural or agronomic practices of weed control like; timely sowing, maintenance of appropriate plant population, selection of suitable crops and crop rotation etc. should be included in the strategy. There are certain crops (black gram, green gram, cowpea etc.) which are prostrate (spreading) in nature and can be included in intercropping systems for the control of weeds.
Additive mixture can control the weeds more efficiently than replacement mixtures. Smother intercrops and live mulch intercrops are high density additive mixtures that appear to offer great promise as means of weed control.
Although, crop rotation has lost prominence in modern agriculture, however, there are still situations where the residual effects of some crops on succeeding crops are of practical importance. Legumes in rotation provide nitrogen to succeeding crops. So also, legumes positively respond to the residual phosphorus.
Several reports pointed out that, poor performance of crops following the sorghum crop. Wilt caused by Fusarium udum is intensified if sole cropping of pigeon pea is continued. It can be reduced by intercropping with sorghum. Intercropping of groundnut with sorghum or pearl millet reduce the incidence of groundnut rust and bud necrosis diseases.
There is erratic nature of rainfall under rain fed situations of the semi-arid regions. Under these adverse situations, it is a challenge to establish and maintain the crop.
If there is a forecast of deficient rainfall in the year, conservation of moisture is the only option to sustain the crops. For the moisture conservation in black soils, deep ploughing during summer season and shallow ploughing in red soils along with the formation of graded furrows, contour farming, bunding and other techniques of moisture conservation should be adopted.
Under the situations of late onset of monsoon, the dry seeding of castor, pearl millet and pigeon pea crops may be followed. Apart from these, the sowing of bunchy type of groundnut genotypes and growing of community nursery of finger millet may be done.
If there is a drought after the sowing of crops, the remedial measures like; re-sowing with the same crop (if the germination has not been proper), thinning of plants, light inter cultivation, use of mulch etc. can be practiced. If the crops like sorghum and pearl millet have suffered with the drought and if there are rains later on, these crops should be left for the rationing.
The re-growth of sorghum is better than pearl millet. These crops either may be used as the fodder or for the grain purposes. If the drought has occurred on the later part of the crop season then supplemental irrigation remains the only option for saving of the crop. In addition to these practices, continuous intercultural operations, mulching and control of pests are also, important for the success of the crops.
Evaluation Factors of Cropping Systems:
Evaluation of any cropping system is being done in different forms. By evaluating the system, we are able to know whether the cropping system is advantageous or not? We can also know from evaluation that, whether the system is capable in efficient utilization of the resources like; soil, water, environment, nutrient elements etc. or not?
The information pertaining to these facts may be obtained by knowing the following evaluation factors whose short descriptions are given below:
Land Use Efficiency (LUE):
Most efficiently used land is one which does not remain idle in a given unit of time. Use of high yield, short duration, photo-insensitive cultivars and better management are common ways to increase the LUE particularly in multiple cropping systems. Mostly 300% and 400% cropping intensity rotations are having maximum LUE.
Efficient Cropping Systems for Fragile Environment:
Apart from normal soil and climatic situations, there are areas where entirely different environmental situations are created such as rain fed lands, salt affected soils, marginal lands and other problematic soils. Intercropping and alley cropping are to be followed in an appropriate planting pattern in such fragile environment to have more production. Intercropping in dry land areas also has risk-cover advantage.
Water Use Efficiency:
For irrigated and rain fed cropping systems separately:
(i) Water efficient cropping system
(ii) Irrigation methods and scheduling
(iii) Insitu soil moisture conservation
Nutrient Use Efficiency:
In modern Agriculture, efficient nutrient management has emerged as one of the most important factors in sustaining high production levels of intensive cropping systems. Widespread deficiencies of N, P, K, S and Zn made these nutrients so important that, successful crop production depends upon the use of these nutrients. Ignoring of any one may lower the efficiency of other nutrients. Thus, balanced use preferably adopting INM may give good results.
Eco-Friendly Cropping Systems:
(i) Systems which help in soil & water conservation (maximum and continuous crop cover favours soil & water conservation).
(ii) System which reduce the use of pesticides in crop production (crops and crop varieties have been identified which are capable of tolerating or resisting certain diseases/insects, pests or weeds through biological mechanism like genetic inheritance, antagonism, allelopathy, growth pattern smothering effects etc.)
Herbicide Use and Cropping System:
Traditional weeds may be controlled by changing the cropping systems, e.g., Johnson grass (Sorghum halepense) of maize can be controlled by rotating with cotton. Adoption of sugarcane-wheat in place of rice-wheat decreases canary grass (Phalaris minor) infestation.
At Kanpur the lowest biomass of nut grass (Cyperus rotundus) was recorded in sesame-wheat as compared to pigeon pea-wheat sequence. Growing of green gram in summer increases the infestation of nut grass. Maize-potato-pearl millet (summer fodder) was found advantageous in reducing nut grass in succeeding crops of maize and potato.
Ground Water Pollution & Cropping System:
Leaching of nitrates and polluting the sub-soil water is a new concern in India and it is all due to application of large amounts of nitrogenous fertilizers containing nitrate-nitrogen. Rice-wheat sequences in Punjab and potato-wheat in other regions are the contributing sequences for more nitrate leaching.
Choice of appropriate cropping systems and management practices helped minimizing nitrate leaching besides improving N-use efficiency. Legume intercropping in cereals reduces nitrate leaching. Sugarcane + black gram and maize + pigeon pea result in low nitrate nitrogen content in soil profile.