Ehiabhi Cyril Odion, Idris Salihu Ahmadu, Ahmed Rufai Aminu, Grace Lamba Luka, Shero Abdulsallam Isah, Uthman Lucky Arunah

Abstract
The paper looks at estimation of the agronomic efficiency (AE) for various crop mixtures at varying levels of fertility management. To evaluate the concept, three trials using different cropping patterns and fertility rates were reviewed by calculating and comparing the relative yield and agronomic efficiency of the main crop. AE was higher in the mixtures compared to the sole crop in all the trials, and in the mixtures while efficiency between the control and the fertility levels employed were high, those between the fertility levels were not as high and increased at a reducing rate, sometimes tending to be constant. These responses gave rise to situations similar to a quadratic response and could therefore permit for optimum fertility levels for crop mixtures to be predicted. This therefore means that sustainable intensification is possible under small scale production systems as increase in efficiency was higher at lower fertilizer rates compared to the higher rates. Assessment of AE for crop mixture could also result in staggered recommended production practices, thus discouraging the excessive use of fertilizers - chemical or organic - and cut cost of production, reduce the pollution of the environment with its attendant consequences while production costs could be within reach of the small scale farmers. Small scale family farmers seeking alternative methods of soil fertility management could be encouraged to undertake the clipping/thinning management of companion leguminous crops as such measures could enhance their productivity as the estimation of AE has shown in these investigations. The practice of either clipping or thinning of the leguminous companion crop is similar or close to current production practices employed by these farmers and therefore should not be difficult to adapt and adopt.

Key words:
Agronomic efficiency; staggered production practices; replacement and additive mixtures; expected yield; green manure.

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