Accumulation of S, Ca, Mg, Fe, Zn and Mn and their relatioship with dry matter production in cowpea grown under minimum and conventional tillage in a Mollisol soil of Venezuela

Abstract

In Venezuela there is a need for information regarding nutrient accumulation by cowpea, Vigna unguiculata L. Walp and their relationship with dry matter production (DM), to improve the efficiency of use of fertilizer, and the amount of nutrient to apply. In this study the absorption of S, Zn, Ca, Mg, Fe and Mn by cowpea (Tuy variety), sowed under minimum (MT) and conventional tillage (CT), was evaluated in a Mollisol soil of the Aragua State. The concentration of the nutrients evaluated were similar in MT and CT, with the exception of S, which was higher in CT. The pattern of the nutrient accumulation was similar in NT and CT, althought the amount of nutrients taken up was higher in CT. Between 11-32% of the S, Zn, Mg, and Fe, and between 55-59% of Ca and Mn were accumulated during the first 43 days after germination (DAG), while between 68-89% of the first, and 45-61% of the latter were accumulated between the 43-58 DAG. Probably in CT, the higher accumulation of nutrients was associated with a lower soil bulk density in the soil layers between 0-10 cm, which improve the development of the root system. In MT there was a quadratic relationship between DM and the amount of nutrient accumulated, which suggest that some other soil factor could affect the nutrient absorption, while in CT there was a linear relationship, which suggest that the crop production could be increased by improvement of the fertilizer management.