Produção de feijão macaçar (Vigna unguiculata (L.) Walp.) e recuperação da fertilidade de um luvissolo via fertilização e inoculação com rizóbio.

Abstract

The soils of the semiarid are suffering a severe degradation process and various techniques are used in the recovery of degraded soils to prop up themselves by providing nitrogen. The objective of this study was to evaluate the responses of different nitrogen sources on the production and recovery of degraded soil in semiarid through the cultivation of cowpea. The experiment was conducted in Experimental farm of Campina Grande Federal University. The chemical composition of the soil was determined before the started experiment. The treatments were: Control group non containing fertilizer and inoculation (T0), NPK fertilizer 120 kg N/ ha, 60 kg P/ ha and 50 kg K/ ha, sources such as urea, simple super phosphate and potassium chloride, respectively (T1), the equivalent to 5 t/ ha of cattle manure + 60 kg P/ha + 50 kg K/ha (T2), inoculation of Rhizobium strain (BR 3267) + 60 kg P/ha + 50 kg K/ha (T3), 60 kg P/ha + 50 kg K/ ha (T4). At 45 days, after emergence, a collection was conducted to evaluate the number, nodule mass and average size of nodules, production of dry matter accumulated in the plant and a total N accumulated in shoots per plant. The presence of nodules during the initial phase of the experiment was significant especially in T3 and T4. Treatment 1 provided the greatest increase in total nitrogen accumulated in shoots, and the other treatments didn’t differ. The relative efficiency of treatments for grain yield over control was 24% for NPK (T1) and the other treatments affected negatively. We observed significantly lower pH in the treatments with manure + PK and NPK as compared to control. The P content in soil increased in all treatments, being more expressive in treatments Inoculated + PK, PK and manure + PK. There were increases in SB, CEC and V in soil (0- 20cm) in all treatments after harvest of the experiment. In immediate terms, only the use of NPK contributed to the increase in N content in shoots of the plant and production of beans monkeys. The sources of fertilizer use contributed to the recovery of soil fertility.