Agri-silviculture and agri-horticulture systems, which integrate trees and crops on the same land, are important sustainable land-use strategies. However, the dynamics of basal soil respiration (BSR) in such systems are not fully unravelled. This study investigated the effects of agroforestry systems on BSR dynamics rate (RBSR) and cumulative CO2 evolution (CBSR) and identified the roles of soil organic carbon (SOC), soil moisture content (SMC) and dehydrogenase (DHA) enzyme activity on BSR. Basal soil respiration was quantified using the alkali trap method over 15 days at 3-day intervals from pre-sowing to crop maturity under 2 agroforestry systems- Tectona grandis L.f. (teak; agri-silviculture) and Phyllanthus emblica L. (aonla; agri-horticulture) and compared with a sole cropping system without trees. Black gram (Vigna mungo (L.) Hepper) and mustard (Brassica juncea (L.) Czern.) were cultivated as understory crops. Distinct temporal dynamics in BSR (RBSR and CBSR) were observed. In black gram, CBSR increased from pre-sowing to flowering (by 24.7 % and 32.4 %) and declined toward maturity (by 10.8 % and 15.9 %) at 0–30 and 30–60 cm depths, respectively. The maximum CBSR was observed in the teak-based system at flowering stage of black gram and mustard that ranged from 2.5–13.3 and 1.9–11.2 mg CO2–C 100 g-1 soil at 0–30 and 30–60 cm depths, respectively. Similarly, at flowering stage of the crops, CBSR ranged from 1.2–11.6 and 0.9–9.1 mg CO2-C 100 g-1 soil and 2.3–9.2 and 1.3–6.1 mg CO2-C 100 g-1 soil in aonla-based system and sole cropping at 0–30 and 30–60 cm depths, respectively. DHA activity (67–77 % variance) was the best predictor of CBSR followed by SOC (36–78 % variance) while SMC played a fair predictor (21–25 % variance). The study highlights the potential of agroforestry systems to enhance soil biological activity and managing soil carbon while supporting sustainable crop productivity.
Sovan et al. (Wed,) studied this question.