Abstract:
The study was conducted in Ottapalam taluk (Palakkad district, Kerala state) to make a comparative evaluation of two cover crops (pueraria phaseoloides and Mucunna bracteata) with respect to yield of biomass, leaf litter addition , nutrient composition , soil enrichment through added nutrient , competition , soil enrichment through added nutrient , moisture regime of the soil and its impact on growth of rubber . The salient findings of study are summarized below. Mucuna bracteata recored higher biomass on per hectare basis than pueraria phaseoloidies . The status of nutrients N, p and k were higher in Mucuna bracteata than pueraria phaseoloides and the difference was much evident in the case of N content. Calcium and magnesium were found to be high in pueraria phaseolodies. The leaf litter from the cover crop was quantified and found that the mucuna bracteata produced higher leaf little (2324.09 kg ha -1) Compared to pueraria (1205.72 kg ha-1). Content of organic carbon, available p and available K in the soil at two depths (0-15 cm and 15-30 cm ) was higher in plots cover-cropped with M. bracteata than other three plots cover-cropped with P. phaseolodies, inter -cropped and those with natural cover. The availability of magnesium was found to be highest in plots inter -cropped with banana . M. bracteata recorded lowest magnesium status of the soil and this can be attributed to the higher up take due to high biomass production . Any sort of the cropping whether cover-cropping or inter-cropping helps to improve the nutrient status of soil and conserve the moisture. The area under natural cover recorded the lowest moisture content during both the months. P. phaseoloides was found to be the most efficient with regard to moisture conservation and recorded the highest moisture content during April and may. Cover –cropping or inter-cropping was found to augment the growth of rubber and maximum girth increment was observed for Mucuna bracteata covercropped plots. The study also revealed that in general Mucuna bracteata was much superior to pueraria phaseolodies with regard to biomass production , and addition of major nutrients to the soil . The low moisture content in Mucuna cover-cropped plots demands further investigations to arrive at definite conclusions regarding the competition for soil moisture between rubber and the cover crop.
