The farmers in Pakistan are mainly growing summer forages (maize, sorghum and pearl millet) as sole crop. Their forage is comprised poor in quality due to low crude protein content. The sowing of cereals in mixture with legumes improved both forage yield and quality. Although some work has been done on growing maize in mixture with legumes but comparative studies on forage legumes including sesbania sown under variable seed ratio is lacking in Pakistan.
Earlier, cropping systems were based on mixtures of desirable species tomeet the basic necessities of life like food, fiber and shelter for the welfare of the community. Mixtures of species were chosen by the growers over the centuries to make use of rainfall and native soil fertility, and choices were made from the best performing combinations observed. “A system of growing two or more crops (or varieties) in the same field, garden or plantation, not in separate blocks with each carrying a single crop but mixed together, occupying the same ground and with identical cultural operations applied to the growing area. “Growing two or more crops simultaneously on the same piece of land with a distinct row arrangements and mixed cropping as being without a distinct row arrangements”.
Mixed cropping of legumes and non-legumes is a very common practice in many parts of the world and particularly in the developing countries. Legumes are the major source of protein for both humans and animals and they also contribute nitrogen to non-legume components when grown in mixture. Mixed or intercropping is a technique for small farmers and intercropping systems of maize with legumes (soybean, cowpea, French beans and curd beans) were superior to sole crops.
Mixed cropping may be more beneficial if the components have different maturity time and growth requirements, have different root system or different morphology, especially in height. Growing of more than one crop better utilizes resources in comparison to mono cropping. Selection of crops for mixed or intercropping includes their compatibility, low competition and ability to produce higher yield as the most important factor.
Component crops in mixture may complement each other nutritionally if one crop requires substantial quantities of an element whilst the other crop has a smaller requirement for this element. This will occur when the growth patterns of crops in association differ in time so that the crops make their major demands on resources at different times. Yield improvement by mixed or intercropping as attributed mainly to the complementary effects better resource use efficiency of the mixed cultures and the buffering effects of the mixtures against diseases and weeds. There were some complementary effects of nitrogen in grass or legume mixtures, which was attributed to the nitrogen fixation by the legume component.
Higher yields from mixtureshave been attributed to more efficient utilization of light by their canopies (caused by differences in height and leaves of the component crops in mixture), efficient use of soil resources due to differences in rooting depth and rooting patterns, the peak growth demand of the component crops occurring at different times and one crop may provide physical support for another or may provide shelter for another. The combination of pearl millet plus cluster bean produced significantly highest LER (1.21) than the intercropping of pearl millet with cowpea. Maximum LER and net return from the intercropping system of green bean as main crop with head lettuce and or green onion. Intercropping system gave the higher LER values in comparison to sole crops.
Mixed cropping, especially with legumes provides a more nutritionally balanced diet to the farmer’s family and quality of yield. Cereals provide the carbohydrate andlegumes provide the protein requirements. Total N accumulation by sorghum in association with soybean was higher than for mono crop. Maximum protein yield of sorghum in soybean plus sorghum system than in sole sorghum. Intercropping on the quanti-qualitative silage production of maize-soybean system and reported that intercropping significantly improved the protein contents. The green and dry forage yields were also highest when maize plus cowpea mixture was sown in rows 30 cm apart.
Nitrogen application to cereal-legume mixtures increases the growth of the cereal component, while atmospheric nitrogen fixation of legumes may be reduced 39. The yield of the non-legume component in a cereal-legume mixture is increased by nitrogen application but the legume component is either unaffected or reduced by nitrogen application. The yield of legumes was reduced with the increase in nitrogen applied level, while the yield of cereal was increased. The leaf area, DM production and seed yield were increased with up to 60 kg N ha-1 but decreased at the at highest application level. Also very little information is available about the chemical composition of forage maize and legumes when sown under variable seed ratio sand nitrogen application.
Zahoor Ahmad*a (PhD Scholar), Muhammad Nasir Iqbal b (MSc),
Muhammad Rehan Aslam b (MSc),Muhammad Irfana (PhD Scholar)and Muhammad Naeema (PhD Scholar)
*aDepartment of Crop Physiology, bDepartment ofAgronomy
UNIVERSITY OF AGRICULTURE FAISALABAD PAKISTAN