Soil phosphorous influence on growth and nutrition of tropical legume cover crops in acidic soil

Authors: FAGERIA, N - Embrapa; Baligar, Virupax; MOREIRA, A - Embrapa; MORAES, L - Embrapa

Submitted to: Communications in Soil Science and Plant Analysis
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/22/2012
Publication Date: 12/19/2013
Citation: Fageria, N.K., Baligar, V.C., Moreira, A., Moraes, L.A. 2013. Soil phosphorous influence on growth and nutrition of tropical legume cover crops in acidic soil. Communications in Soil Science and Plant Analysis. 44:3340-3364.

Interpretive Summary: In low fertility acidic soils of the tropical regions, phosphorous deficiency is one of the most limiting factors for effective cultivation of legume cover crops. Better understanding of cover crop species that have high phosphorous use efficiency can improve the sustainability of cropping systems in infertile tropical soils. In this paper we report the finding of cover crop species that have high phosphorous nutrient use efficiency at low to high soil phosphorus levels. In the tropical region, these high nutrient utilizing cover crops in low soil fertility will be effective in improving soil fertility, recycling of nutrients, control of pests and weeds and improving microbiological activities. This information will be of use for tropical farmers to develop cover crop technology to halt soil degradation and to develop sustainable and low input crop management systems for row and plantation crops. Farmers, scientists and extension workers who need to develop improved sustainable cover crop management systems in low fertility tropical soils will benefit from this research.

Technical Abstract: In tropical regions, the use of cover crops in crop production is an important strategy in maintaining sustainability of cropping systems. Phosphorus deficiency in tropical soils is one of the most yield limiting factors for successful production of cover crops. A greenhouse experiment was conducted to evaluate influence of phosphorus (P) on growth and nutrient uptake in 14 tropical cover crops. The soil used in the experiment was an Oxisol and phosphorus levels used were low (0 mg P kg-1), medium (100 mg P kg-1) and high (200 mg P kg-1). There was a significant influence of P and cover crop treatments on plant growth parameters. Phosphorus X cover crops interaction for shoot dry weight, root dry weight and root length was significant, indicating different responses of cover crops to variable P levels. Based on shoot dry weight efficiency index (SDEI), legume species were classified into efficient, moderately efficient or inefficient groups. Overall, white jack bean, gray mucuna bean, mucuna bean ana and black mucuna bean were most P efficient. Remaining species were inefficient in P utilization. Macro and micronutrient concentrations (content per unit dry weight of tops) as well as uptakes (concentration x dry weight of tops) were significantly (P < 0.01) influenced by P as well as crop species treatments, except Mg and Zn concentrations. The P x crop species interactions were significant for concentration and uptake of all the macro and micronutrients analyzed in the plant tissues, indicating concentrations and uptake of some nutrients increased while others decreased with increasing P levels. Hence, there was an antagonistic as well as synergetic effect of P on uptake of nutrients. However, uptake of all the macro and micronutrients increased with increasing P levels, indicating an increase in the dry weight of crop species with increasing P levels. Overall, nutrient concentration and uptake in the top of crop species were in the order of N > K > Ca > Mg > S > P for macronutrients and Fe > Mn > Zn > Cu for micronutrients. Inter-specific differences in shoot and root growth and nutrient uptake were observed at varying soil P levels.