Unlike intercropping crops are grown one after another in sequential cropping and hence, management practices are different.
Short duration of crops are selected to fit well in the multiple cropping systems. Photo- insensitive varieties are essential for successful sequence cropping system. Most of the high yielding varieties.
2. Seedbed Preparation:
Suitable can be prepared as per crops. Puddling for rice, ridges and furrow for vegetable, maize and cotton and flat seedbed for several other crops. However, two problems are encountered in seedbed preparation in sequential cropping system.
1) The time available for seedbed preparation is less in high intensity cropping system. Frequent rain interference the land preparation.
2) Due to prevent crop field may be in condition. For example field preparation after rice is difficult, it is mainly because soil structure is destroyed during puddling.
The turn – around time, the time between harvesting of crop to sowing of next crop in more if rice is the preceding crop. To avoid this problem minimum tillage or zero tillage is adopted. It is the common practices to sow pulse crop just before or immediately after harvesting. Rice crop. In rice- wheat system the stubbles are killed by spraying Paraquat and wheat is sown in plough furrows between stubble of rice.
In irrigated agriculture the time available for tillage between two successive crops is minimal leading to minimum tillage. Minimum tillage is applicable for soils with, 1.A course texture surface soil, 2.Good drainage 3.High biological activity of soil fauna. 4.An adequate quantity of soil residue mulch. And 5.Favourable initial soil moisture and friable soil consistency over a wide range of soil moisture.
It is not possible to practice zero or minimum tillage in all sequence cropping systems. If sunflower is the preceding crop, ploughing is essential to oxidize the allelo chemical of sunflower. The stubbles of pearl millet and sorghum, which contain high C:N ratio immobilizes nitrogen. It is therefore, necessary to remove them. Stubble also interfere the operations.
In rice-rice-green gram system summer ploughing is done and later when water is available in the rainy season puddling is done and first crop is sown. For the second rice crop minimum tillage as incorporation of crop residues and rice is planted. Green is sown as a relay crop in the second rice crop.
In Cotton-Sorghum-finger millet cropping system in garden lands, thorough field preparation is done and field is laid out into check basins to transplant finger millet. In next season, cotton is planted among the stubbles of finger millet without any kind of preparation. Weeds are controlled by Intercultivation operation in Nigeria, no till planting of sorghum into residues of the previous crop maintained the seed at 10oc lower temperature in the seedling zone reaches 41oc.
Sowing is not a problem as provided sufficient time for seedbed preparation. If seedbed not prepared well, difficult the establishment of crop for example- cotton establishment is difficult in black soil after rice. Due tom hard pans in the shallow layer, root penetration is difficult. If field allowed to dry for land preparation, lost of one month, hence seedling are raised either on twisted paddy straw of leaf cups before harvesting of rice crop. After harvesting a cow bar hole is made up to 30 cm. it is partly filled with sand and soil mixture and cotton seedling are planted. The establishment of pulse crop is difficult after rice broadcasting of seeds rice crop or rice subjected results uneven germination and high seed rate is necessary. Crops planted in stubbles are subjected to competition from regenerated stubbles. It can be overcome by spraying preparation or digger on stubbles.
Delay in sowing is common problems in intensive cropping systems. To reduce yields loss due to transpiration of overage seedlings. Higher level of nitrogen is applied to induce tillering. In rice – wheat system, wheat yields are reduced considerably when the sowing of wheat are delayed beyond November. In such situation, transpiration of 40 to 50 days old seedlings of wheat is done. FYM is broadcasted over the field to maintain higher soil temperature during December.
4. Soil fertility management:
Soil fertility management become more complex in intensive cropping because of the additional factors such as residual effect of nutrients applied to the previous crops, possible effect of legume in the system, complementary and competitive interaction from the component crops and influence crop residues left in the soil. The modern or chemical agriculture, which in ludes higher cropping intensity involving improved varieties, heavier inputs of fertilizer and water, increasing yields and accelerated removal of plant nutrients have inputs of fertilizer and water, increasing yields and accelerated removal of plant nutrients have added newer dimensions to the fertility management.
Fertilizer practices for sequence cropping: based on long term fertility experiments conduced in various parts of India, the following broad conclusions are :
System productivity increased with the application of P along with N, and further increased with use of N, P and K, Application of N at recommended dose is advocated to each of the in cropping system.
Phosphorus management in cropping system needs careful adjustment of P fertilizer dose taking into the account type of fertilizer, soil characteristics and their yield level, extent of P removal and growing environment. In cropping system – involving wheat, fertilizer P dose to Kharif crop crop can be reduced if preceding wheat has received P in adequate amounts.
Removal of K in proportion to N is very high in cropping systems. Particularly those involving cereal and fodder crops. It is important to apply K fertilizer are recommended dose to maintain soil fertility. In K rich soils of Coimbatore, K application at 50% recommended dose to each crops in the sequence rice-rice-soybean was optimum. Among the secondary nutrients, sulphur application is benefited particularly to sesamum- mustard, soybean- safflower and groundnut- mustard cropping sequence (Tondon, 1991)
Among micronutrients, Zn deficiency is the most common as nearly 50% soils of intensive cultivated areas suffers from Zn deficiency. Rainy season crops like rice, maize and sorghum respond more to applied Zn than winter crops like wheat and chickpea. Under long term experiments at Ludhiana (Punjab), significant decline in productivity of maize was recoreds after 10to 12 years’ annuals cycles, due to fall in Zn status. Use of organics prevents Zn deficiency in intensive cropping system under normal soils.
5.Cropping System and Integrated Nutrient Management (INM):
The concept of integrated nutrients management (INM) involves use of various inorganic, organic, biological sources of nutrient for improvement and maintenance of soil fertility leading to sustained crop production. Crop responses to organic and biological sources of nutrients for improvement and maintenance of soil fertility leding to sustained crop production. Crop responses to organic and biological sources of nutrients are not spectacular as to fertilizers, but the supplementary and complementary use of these resources is known to enhance the use efficiency of applied fertilizer besides improving soil physico- chemical properties and preventing emergence of micro – nutrient deficiencies.
The major components of the INM are fertilizer, organic manures, green manures, crop residues and Biofertilizers. In cereal- based cropping systems, about 25-50% fertilizer NPK dose of rainy season crops could be curtailed with the use of organics such as FYM, green manure and crop residues. In sugarcane based system, integrated use of sulphitation press- mud, cane trash and Biofertilizers each with inorganic fertilizers and green leaf manuring showed 20-25% economy of fertilizers N applied to sugarcane by improving the use efficiency of N, P and other nutrient.
Effect of intensive cropping on soil properties: physical properties- continuous ground cover due to intensive cropping minimizes soil erosion, run-off losses and crust formation. Relatively higher amount of crop residues due to intensive cropping improves soil structure.
Chemical Properties- Organic residues in intensive cropping systems should be recycled to maintain optimum organic carbon in the soil for sustained production.