On-Farm Management of Persea Americana (Avocado) and its Influence on Some Soil Physicochemical Properties and Maize Yield: A Case of Damot Gale, South Ethiopia

Abstract

On-farm trees are known to contribute to biophysical and economical sustainability at farm and landscape levels. This study assessed the contribution of on-farm avocado tree on some selected soil fertility parameters and maize yield, and explored farmers’ local knowledge, the influence of avocado on maize production and soil fertiliity at Aro-Wagera, Damot Gale, Southern Ethiopia. Soil samples were collected from under the canopies of four avocado trees at four radial distances (0.5-1, 2-2.5, 4.5-5 and 16m) away from the trunk and at two depths (0 – 15cm and 15 – 40cm) for each radial distance. The soil samples were analyzed for physical and chemical properties. The soil textural class of the soil was sandy loam at both depths and all radial distances. There was no significant difference in the textural classes between samples taken from open field and under the canopy. The bulk density showed increasing trend with increasing depths and positively and significantly correlated with distances from the tree trunk to open area. Chemical properties including, available P, total N, organic carbon, soil pH, and CEC had decreasing tendency with increasing depths and four radial distances from the tree trunk. The local knowledge was gathered by involving seven KI, 35% of HHs from the total of 206 HHs over the studied area. Random sampling technique was used to selected  the HHs from each of the three wealth categories. Both informal and formal surveys were employed. Households with different wealth categories have different strategies in managing avocado tree grown at different niches. The interviewed farmers indicated that avocado tree have negative influence on maize production. The farmers view is supported by quantitative analysis. Tree-maize interaction showed reduction of maize yield under the tree canopy compared with open area. On the hand, the farmers’ perception that avocado tree depletes soil nutrient was not supported by soil analyzed. In conclusion, on-farm avocado tree influence soil nutrients grown on ic Nitosols (which is equivalent to Ultisols) in research site do not influence fertility of soil under their canopy. Indeed, the tree can be regarded as parkland agroforestry trees to integrate them with maize production to enhance the sustainability of soil fertility.

Key words: Local knowledge, Income, Parkland , Soil fertility