Impact of organic fertilization on establishing an agroforestry system in a semi-arid Brazilian region

Improving soil fertility with organic sources is crucial, particularly in degraded regions. Organic fertilizers, when integrated into systems, provide cost-effective solutions. This study aimed to assess the impact of various organic fertilizers on the establishment of an agroforestry system in Planosol in a semi-arid region of Ceará State, Brazil. We used a randomized block design arranged in split plots. Four organic fertilizer sources (sheep manure, cattle manure, carnauba palm straw, and control) were assigned to the main plots. Evaluation years for annual crops (2015, 2017, and 2019) and for trees (2015 through 2017, and 2019) were allocated to subplots, with three replicates. All organic fertilization sources received an annual rate of 10 t ha-1, broadcasted uniformly. Experimental plots, spanning 18 x 7 m, were intercropped with maize and cowpea between rows of trees (Mimosa caesalpiniifolia and Spondias mombin). We examined soil fertility, tree growth, and crop grain yield. Soil chemistry, notably P and K, showed marked improvement with sheep manure. Organic fertilization did not enhance tree growth in the newly established agroforestry system. However, organic fertilization elevated maize and cowpea grain yields by over 60% and 90%, respectively, compared to the control. In conclusion, the use of sheep manure, cattle manure, and carnauba palm straw can significantly boost maize and cowpea grain yields in an agroforestry system found in the semi-arid region of Ceará, Brazil.