Intercropping

Inter cropping is the agricultural practice of cultivating two or more crops in the same space at the same time.
  • Inter cropping also uses the practice of sowing a fast growing crop with a slow growing crop Ragi is grown under rainfed conditions mixed or inter cropped with sorghum, pearl millet and various oilseeds and pulses.
  • The most common subsidiary crops grown ragi are field bean (Lablab purpureus), pigeon pea (Cajanus cajan), cowpea (Vigna sinensis), and Niger (Guizotia abysinnica).
  • With groundnuts, ragi is the subsidiary crop.  In hills it is grown mixed with soybean.
Some of the common rotations are given below:
  • Ragi + Pigeon pea combination in 8:2 or 6:2 proportion brings higher returns.
  • Ragi + field bean in 8:1 proportion resulted in enhancing the productivity.
  • Ragi + Fodder sorghum in 8:1 proportion resulted in enhancing the productivity in Karnataka.
  • Ragi + black gram or green gram in 8:2 proportions is the other profitable crop combinations.
  • Pearl millet is often grown in rotation with sorghum, groundnut, cotton, foxtail millet, finger millet (ragi), castor, and sometimes, in the south India, with rice. On the red and iron rich soils of Karnataka, pearl millet and ragi rotation is practised although pearl millet isn’t always grown annually.
  • Maize and millet intercropping is the best planting arrangement to produce the highest yield. The intercropping environment also minimized the occurrence of disease and lodging in millet. The combined yields of the different intercropping combinations were 5-25% higher than that of a mono crop.
  • Intercropping of finger millet (transplanted) + pigeon pea in the row ratio of 4:1 is better in terms of  finger millet equivalent yield (66 q/ha), net returns (Rs. 20 thousand/ha) under rainfed condition.
  • Sometimes the ragi intercropped with mustard, because mustard flowers bloom during the early stages of the ragi crop and attracts lady bird beetles, a predator of aphids, attacking the ragi crop. In case of rain failure, mustard acts as an insurance crop.
  • Ragi – Maize (2 year crop rotation) gave higher yield per unit area as compared to Ragi – Ragi crop rotation.

 

A Generation Ago in India.

  • Land in the north was devoted to producing only wheat, but with the advent of earlier maturing, high-yielding wheat and rice, it became possible to harvest the wheat in time to plant rice.
  • This wheat/rice combination is now widely used throughout Punjab, Haryana, and parts of Uttar Pradesh.
  • The rice yield of 2 tons per hectare and the wheat yield of 3 tons combine for 5 tons of grain per hectare, making it a key to feeding India’s 1 billion people.
  • The area that can be multiple cropped is limited by the availability of irrigation water, early-maturing varieties and in developing countries, enough labor to quickly harvest one crop and plant another.
  • The loss of low-cost rural laborers through the processes of industrialization can sharply reduce multiple cropping and therefore the harvested area.
  • In Japan, for example, the grain-harvested area in 1961 reached a peak of nearly 5 million hectares, because farmers were harvesting an average of two crops per year.
  • As of 2002, the harvested area had dropped to 2 million hectares partly because of cropland conversion to nonfarm uses but mostly because of a dramatic decline in double cropping as industry pulled labor from agriculture.
  • Even a rice-support price four times the world market price could not keep enough workers in agriculture to support extensive multiple cropping.
  • South Korea’s harvested area has shrunk by half since peaking in 1965.
  • Taiwan’s has declined nearly two thirds since 1975.
  • As industrialization progresses in China and India the more prosperous regions of these countries may see similar declines in multiple cropping.
  • In China, where incomes have quadrupled since 1980 this process already appears to be reducing production.

Intercropping Nitrogen- Fixing Shrubs in RWANDAN Coffee Farms

  • The shrub Tephrosia vogelii can grow very quickly up to 4 meters high fixes nitrogen and can be used as green manure.
  • In Maraba, Southwest Rwanda, coffee productivity is constrained by poor soil fertility and lack of organic mulch.
  • A 2-year study on 8 smallholder coffee farms trialled the effect of intercropping Tephrosia and coffee.
  • The mulch produced from Tephrosia was also used on the coffee plots. In the first year, Tephrosia intercropped with coffee produced 1.4–1.9 tonnes per hectare of biomass and added 42kg–57kg of Nitrogen per hectare.
  • This treatment increased coffee yields by 400kg–500kg per hectare, compared to traditional management methods.
  • In the second year Tephrosia produced between 2.5–3.8 tonnes per hectare of biomass and added 103kg-150kg of Nitrogen per hectare.
  • This increased yields of coffee by 400kg per hectare.
  • Over the 2-year study, coffee yields increased between 23% and 36%.
  • Tephrosia mulch was 87% as efficient as inorganic fertiliser used under similar conditions, and represented a saving of 30 days of labour hours per hectare compared to current farmer management through reduced labour required for weeding.
  • Together the labour savings and the improved yields translated into the farmers producing 5kg of coffee per labour-day compared to 3.4kg per labour-day under traditional management.

Mbili Intercropping

  • Farmers in Western Kenya traditionally row-crop maize with nitrogen-fixing legumes to increase yields and soil fertility.
  • Nitrogen is returned to the soil from the falling leaves and decomposing roots of the bean plants.
  • Researchers at the Sustainable Agriculture Centre for Research Extension and Development in Africa (SACRED-Africa) noticed that the single rows were not providing enough light for the legumes and that the second maize crop often failed due to insufficient late rains.
  • To address these constraints they pioneered a new system known as MBILI (Managing Beneficial Interactions in Legume Intercrops) meaning “two” in Swahili.
  • MBILI consists of intercropping double rows of maize and legumes allowing for better light and soil conditions whilst maintaining the same plant populations.
  • The system yields nearly 3 tonnes of maize and more than 500kg of legumes per hectare.
  • MBILI has been shown to increase production by 26% – 37% in the short rain season and around 7% in the long rain season.
  • The greatest improvement is noted in groundnut which can increase by 101% compared to conventional conditions.
  • Farmers earn an average of 31,689 KSh (US$325) per hectare using MBILI Intercropping, compared to 26,333 KSh (US$270) with conventional methods.

Faidherbia

  • Faidherbia albida is a nitrogen-fixing Acacia tree that is widespread throughout Africa growing in a variety of soils and climates.
  • Faidherbia is able to make large quantities of nitrogen available to nearby crops and increase the store of carbon above ground and in the soil.
  • It sheds its leaves in the wet season and retains them in the dry season allowing for light to pass through in the wet season whilst providing residue in the dry season.
  • As a consequence it is possible to plant and grow maize under the trees.
  • Yields can reach more than 3 tonnes per hectare without fertilisers, depending on the amount of nitrogen fixed by the trees.
  • The trees also contribute 2 tonnes or more of carbon per hectare to the soil and mature trees can store more than 30 tonnes of carbon per hectare.
  • In Malawi, Faidherbia provided 300kg of fertiliser per hectare and boosted unfertilised maize yields from 2.5-4 tonnes per hectare, 200% to 400% more than national averages when planted every 10 rows.
  • In a survey of 300 farmers in the Dedza district of Malawi, those that grew Faidherbia did so in order to improve soil fertility on their farms (starting when the trees are 4 to 6 years old) did not use nitrogen fertiliser and were keen to grow more trees.
  • In Niger, Faidherbia has been planted on almost 5 million hectares of land leading to similar benefits.
  • The climate change mitigation potential for systems incorporating trees with fertilising properties lies in their ability to sequester between 2 and 4 tonnes of carbon per hectare per year compared with 0.2-0.4 tonnes of carbon per hectare per year under conventional conservation farming systems.
  • However, Faidherbia trees take 6 years to fully develop, making investments hard to justify particularly if land tenure is insecure and/or farmers are dependent on immediate benefits and incomes.
  • At present Faidherbia is grown on only 2% of Africa’s maize area and 13% of sorghum and millet area.

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