EFFECT OF SOWN DATE OF VELVETBEAN (MUCUNA SP) AS COVER CROP ON YIELD GRAIN OF MAIZE

Abstract

Milpa system was development almost three millennia in the Mayan area Mesoamerican. It is based on the management the vegetation with prolonged period of fallow; and short time for cultivation of maize and the wide crop biodiversity. Today, due to greater pressure on resources, the fallow period has been reduced, consecuently also the grain yield of maize, attributed to low fertility of soil and weed increase. Cover crops contribute to solving some problems associated with the milpa system. However, little is known the functioning of these in conditions of low rainfall and permeable soils. Thus, the planting date of cover crops plays a key role in the management of biomass and in the main crop. Therefore, the objective of this work was to evaluate the following treatments: 1) control, maize without velvetbean (VB), 2) simultaneous planting of VB with maize (0 DASM), 3) VB planting at 20 days after maize (20 DASM), 4) VB planting 40 days after the maize (40 DASM) and 5) VB planting 60 days after maize (60 DASM). We used a Latin Square 5 x 5 x 5 experimental design, the variables registered were: yield grain and their components; nitrogen content, phosphorus and potassium soil in the full-grain phase of maize; and nitrogen content, phosphorus and potassium in the grain of maize, pod and grain of the VB. Simultaneous planting and 20 DASM of the VB reduced the yield of grain of maize in 59 % and 25 %, respectively. The yield grain of maize was adjusted to the equation y=-0. 5525X 2 + 48. 54 X + 606. 3 (R2 = 0.96), while the stubble was y=-0. 648 X2 + 65. 632 X + 3989.7 (R2 = 0.99). Nitrogen of soil was reduced in the simultaneous planting (P<0.05), while that the phosphorus and potassium interchangeable were not affected by the treatments. The contents of nitrogen, phosphorus and potassium in the grain of the maize and in the sheath and grain of VB were not affected by treatments. In conclusion, the simultaneous date and 20 DASM reduce the yield of grain and stubble of maize, therefore, for a better use of VB as cover crops should be considered other management strategies to optimize the biomass production and their utilization.