**6. Interference of agroforestry in soil health management**

The agroforestry system increases the soil infiltration capacity. In an experiment, it was reported that the infiltration capacity of soils which were mostly clay to silt clay in texture and acidic in nature were in the order of Eucalyptus, Bhabar, Eucalyptus + Bhabar, and agricultural plot. The infiltration rate was about 3 times in Eucalyptus + Bhabar than the agricultural plot [52]. The effects of five agroforestry systems on soil physical properties have been investigated in the ICAR complex for the north-east region in India. The name of the agroforestry systems are Khasi mandarin (*Citrus reticulate* Blanco.) + annual agricultural crops; Assam lemon (*Citrus lemon* L.) + annual agricultural crops; Arboretum (Mixed multipurpose tree species) + annual agricultural crops; Silvi-hortipastoral [alder (*Alnus nepalensis*) + pineapple (*Ananus sqennnsa* L.) + fodder and multistoried AFS [alder +tea (*Camellia sinensis*) + black pepper + annual agricultural crops]. The soil physical properties such as bulk density (BD), mean weight diameter (MWD) and apparent saturated hydraulic conductivity (AHC) were compared with the soil from the adjoining area of natural forest soils of same age. The mean bulk density of soil from natural forest was least (0.94 Mgm−3) and highest for Khasi mandarin and Assam lemon (1.19 Mgm−3). The bulk density was less for natural forest and other agroforestry systems due to heavy litter fall and decay of dead roots resulting in high organic carbon content [8]. Soil aggregates were represented with MWD which was observed highest for natural forest i.e., 3.13 and lowest in case of Assam lemon i.e., 1.39. The value of MWD is in the order as natural forest>multistoried AFS > Silvi-hortipastoral>Arboretum>Khasi mandarin>Assam lemon. The value of MWD was highest for natural forest due to more availability of organic matter content which helps in forming the aggregates. The reason for being a low value of MWD for Arboretum, Khasi mandarin and Assam lemon may be attributed to the frequent use of agricultural implements that disintegrate the soil structure. In all agroforestry systems, hydraulic conductivity was inversely related to soil depth. AHC signifies the rate of water movement through the soil profile. AHC was found rapid in natural forest (1.84 x 10−4 m/s) and least in case of Khasi mandarin system (0.38x 10−4 m/s). AHC varied for different agroforestry systems as Natural forest>multistoried AFS > Silvi-hortipastoral>Arboretum>Assam lemon> Khasi mandarin. This study concludes among the agroforestry system, multistoried AFS and Silvi-hortipastoral improves more soil moisture conservation capability, soil structure, and pore size distribution [53].

An increase in porosity was reported by Udawatta et al. [54] in the Midwest Region of the United States in maize-soybean field in conjunction with using agroforestry buffers. In grass and agroforestry buffer strips pore path was observed three and five times higher than in soil of maize-soybean field which may be a reason for increased infiltration rate. Pandey et al. [55] reported that the sand particles declined by 10% and 9%; clay particle increased by 14% and 10% under midcanopy and canopy edge respectively compared to under canopy gap position. Silt particles quantity was not influenced by canopy position. Soil organic carbon, total N, total P were more under mid-canopy and canopy edge compared to the canopy gap. Seobi et al. [33] observed improved soil physical properties in agroforestry and grass buffer system in comparison to the row crop system.
