The association of mulch cover and organic fertilization improves the agronomic performance of millet under rainfed cultivation in the semi-arid environment

This study aimed to evaluate the agronomic performance of millet in response to the application of organic fertilizer combined with different levels of mulch cover on the soil. The research was carried out in the Brazilian semi-arid. The experimental design was randomized in blocks under split plots, with four replications. Five levels of mulch cover were applied (0, 1, 2, 3, and 4 Mg DM ha-1), and tested combined with and without organic fertilization (30 Mg ha-1 of cattle manure). The agronomic characteristics of millet cultivar were evaluated: stem length and diameter, number of tillers, inflorescence length, leaf area, leaf area index; gas exchange (photosynthesis, stomatal conductance, and instantaneous water use efficiency); and the dry mass yields. In general, morphological traits, CO2 assimilation rate, stomatal conductance, and water use efficiency were improved by the use of organic fertilizer combined with the increasing levels of mulch cover. The greatest number of tillers per plant (5.75) was observed with organic fertilization combined with the application of 4 Mg DM ha-1 of mulch cover (p<0.05). The greatest level of mulch cover could increase photosynthesis by 79%. The application of mulch cover at the level of 4 Mg DM ha-1 favored better growth responses and yields of the millet. The use of mulch cover potentialized the effects of the organic fertilizer on the millet.