Pigeon Pea as Cover Crop

A cover crop can be sown between cropping operations or as a companion crop during the early stages of crop development. An example of a cover crop system used in the Philippines is sowing mungbean with maize. The mungbean are either sowed at the same time with maize as intercrop or as relay cropping or a crop after maize (crop rotation). There is however some difficulties in the use of cover crops. One is competition for soil moisture and sunlight with the cash crop.

Maintaining ground cover either as an intercrop, relay, or crop in rotation is critical in reducing the effects of raindrop impact and soil aggregate disintegration. Ground cover prevents raindrops from directly striking the soil surface and allows rainfall to slowly penetrate the soil surface. Thus, reducing the amount of rainfall that goes to runoff and make more water available for plant growth.

There are a number of options to maintain vegetation or cover during and between cropping operations. One is stubble’s retention; retaining surface stubble provides ground cover and organic matter during fallow periods and successive crops. Advantages of stubble include no competition with the crop in terms of moisture and reduced herbicide use. However, there could be some difficulties in sowing seeds directly to the crop stubble’s specially ion thick-stubbles. These difficulties with tillage and sowing through the stubble may be overcome by finely chopping the stubble before sowing and modifying direct drilling equipment.

As a Conservation man working on Soil Fertility maintainance and rehabilatation, we want to share our new experience in terms of cover crop.  Right now through the JIRCAS Project, we are working on Conservation tillage (Minimum  or Zero Tillage) in Ilagan, Isabela.  We are trying to validate the effects of conservation tillage and  conventional tillage (intensive plowing and harrowing) in sloping areas planted to corn.  We are also testing cover crops that will not only protect the soil from the effect of heavy rainfall but at the same time will produce enough biomass that can be used as mulch and later on will decompose and add organic matter to the soil.

In this project, initially, we tried mungbean as inter crop to corn.  We intend to use this as soil cover during the time that corn as the main crop is not growing in the field.  Mostly, this time is during the turn over period after harvest of the May to September crop and before the start of October to February crop.  We want that because after corn harvest in September, it leaves the soil bare and prune to erosion because during the month of September and October,  we always experience heavy down pour.

Results of our work suggest that mungbean is a good crop that can add income to the farmer as it can produce pods and a very good source of protein.  However, as cover crop, it cannot serve our purpose of protecting the soil during the turnover period.  It has very short life cycle and usually harvested earlier than the main crop.

Realizing that mungbean will not serve the purpose, we tried pigeon pea.  In the very first cropping that we have, we noticed that pigeon pea is a good dry land crop.  We planted pigeon pea in the farmers field during the month of February and it survived even without watering (February, March and April are dry months in Ilagan, Isabela) until the month of May, where we experienced the first rain.  Pigeon pea can produce heavy biomass that can be used as mulch and add soil organic matter.  During the the first two months of corn, pigeon pea should be pruned twice a month or else it will out grow the corn.  Then, even if you cut the pigeon pea on the first node of branching, it recovers very past.  It has also very good root system.  Root development can extend as much as 70 cm deep even if the plant is maintained by cutting at about knee high.  The deep root penetration is very important in recycling nutrient from the deep horizon back to the surface.

When we harvested the corn, and allow pigeon pea to re-grow, it continuously bear flower and initiate podding.  This is very good for the farmers.  Since pigeon pea is producing so much biomass, mulch to protect the soil is ensured.  Weed growth is also suppressed. Additionally, because pigeon pea is producing heavy biomass, increase in soil organic matter content is remarkable.

Pigeon pea is also a good feed for the livestock.  In one of our site (SWMS), they are growing goat, and these animals love to eat pruned leaves of pigeon pea.  Care takers of these animals are now inquiring us where can they source pigeon pea seeds.  If possible, they want to try growing pigeon pea and feed the leaves on their livestock.  Farmers in the vicinity of our project in San Antonio, Ilagan, Isabela are beginning to notice the beauty of pigeon pea.  In fact, they are now starting to ask how can they source seeds and plant in the area.

We have just started using pigeon pea as cover crop, initial results are very promising.  We will continue to work on it…

Pigeon pea used as cover crop (JIRCAS-BSWM Project; Ilagan, Isabela; 2008)