Nutrient use Efficiency and balance sheet of nutrients under MYR in cassava

Abstract

Efficient use of nutrients is an essential goal in crop production. The fraction of the nutrient from the total applied quantity really decided the biomass of the crop. By distinguishing the biological and economical yield, the efficiency of nutrient use can be defined from the recovery of available or applied nutrients as the ratio of kg biomass or kg grain to kg nutrient applied. Cassava being a biologically crop in converting solar energy to chemical energy and having good response to applied manures and fertilizers, an attempt was made under Maximum Yield Research (MYR) in cassava to compute the agronomic efficiency and balance sheet of nutrientsafter two years of continuous cropping. The study revealed the highest use efficiency of N, P and K with optimal level of these nutrients (NPK @100:300:300 kg ha-1) along with FYM @12.5 t ha-1. The use efficiency of N decreased with increase in the level of N, but increased with increasing level of P and K. Similarly, increasing levels of N and K favoured use efficiency of K but incremental doses of P diminished P use efficiency. The agronomic efficiency of K was seen promoted with increasing level of N and P but higher rates of K nutritionalso reduced the agronomic efficiency of K. The influence of FYM in modifying the use efficiency of these nutrients was not consistent during both the seasons.Studies on the nutrient balance sheet for available N,P and K showed a deficit balance for these nutrients after two years of experimentation but a net gain was noted for N and K after the first crop. But application of higher levels of one nutrient led to reduction in the loss of the other nutrients.