Sapota (Achras zapota) based bio-engineering measures for slope stabilization and sustainable productive utilization in Mahi ravines, Gujarat

A long-term field experiment (2010-2022) was conducted on 14% sloped ravine lands along the Mahi River in Gujarat to evaluate agroforestry systems integrated with bio-engineering techniques for runoff conservation, soil loss reduction, and productivity enhancement. Five treatments were tested on 72 × 24 m plots: (i) cowpea + castor on bench terraces (CCBT), (ii) sapota + cowpea + castor on bench terraces (SCCBT), (iii) sapota on bench terraces (SBT), (iv) sapota with staggered trenches on slope (SSTS) and (v) sapota on untreated slope (SS - control). Bench terraces were subdivided to reduce slope length; staggered trenching involved 96 trenches (2 × 0.5 × 0.5) m. Tree spacing was 8 × 8 m; Cowpea and Castor were intercropped at 0.3 m spacing. Data on plant growth, yield, runoff, and soil loss were collected using a randomized block design with four replications for crop components, while runoff and soil loss were monitored in a single replication. Results showed that SCCBT achieved the best outcomes: maximum sapota height (4.58 m), stem diameter (13.06 cm), fruit count (256/plant), fruit yield (3672 kg ha-1), and crop equivalent yield (3953 kg ha-1). It also recorded the highest energy efficiency (362%), lowest runoff (96.83% reduction), and soil loss within permissible limits (9.27 t ha-1yr-1). Water productivity peaked at 6.54 kg-1ha-1mm, with a net return of ` 41,726 ha-1yr-1. These results demonstrate that the sapota + cowpea + castor system on bench terraces is the most effective bio-engineering solution for slope stabilization and sustainable land use in the Mahi ravines.