Atlantic Forest soil as reference in the soil quality evaluation of coconut orchards (Cocos nucífera L) under different management

Abstract

The evaluation of the soil quality is important to identify potential problems of soil degradation.The assessment of the soil quality requires the determination of several soil parameters and the integration of specific soil properties measurements into mathematical models, such as the soil quality index (SQI).The aims of this study were to: (i) determine the SQI for an Ultisol under a remnant of Atlantic Rain Forest; (ii) use the SQI for the Atlantic Rain Forest as a reference to evaluate the effects of conventional and integrated management in coconut orchards. It was hypothesized that the conventional management of coconut (Cocos nuciferaL.) orchards reduces the SQI compared with Atlantic Rain Forest. A soil quality index was constructed using an additive model that considered three main soil functions (the ability of the soil to promote root growth, water storage and flux, and nutrient supply) and a set of soil indicators. The SQI values were 0.66, 0.54 and 0.46 for the Atlantic Forest,integrated and conventional orchards, respectively; therefore, there was decline in soil quality in both orchards. Even though there was an increase in the organic matter content in the integrated coconut orchard as result of the maintenance of the organic residues on the soil surface and the presence of cover crops, the SQI indicated that, in that type of highly weathered soil, a more conservative approach needs to be applied to avoid further soil quality degradation.