Agricultural Water Management (Oct 2024)
Determination of the optimum depth for subsurface dripping irrigation of sugarcane under crop residue management
Abstract
Sugarcane cultivation covers a large area of agricultural land in southwestern Iran. Considering the high water demand of sugarcane and Iran's limited water resources, optimizing efficient Subsurface Drip Irrigation (SDI) systems is key. To support the design of SDI systems, we conducted an on-farm split-plot experiment in southwestern Iran, investigating the effect of dripper installation depths and mulch on crop and soil properties (medium soil texture). The main factor was mulch management comprising M1: the incineration of crop residues, and M2: leaving sugarcane residues on the soil surface after harvest. The sub-factor was SDI at three installation depth (ID) of the laterals: ID1: 15 cm, ID2: 25 cm, and ID3: 35 cm. The main and interaction effects of treatments were investigated on the vertical and horizontal distribution of soil moisture, salinity, and nitrate, and on the quantity and quality of sugarcane yield. The results illustrated that with increasing the dripper installation depth from 25 to 35 cm in average, soil moisture increased (4.4 %) and soil salinity and nitrate decreased by 17.5 and 11 % respectively, which also resulted in 11.2 % non-significant decrease in yield. Using mulch saved moisture by 18.4, 5.7 and 5.3 %, but decreased salinity by 27.2, 22.9 and 21.9 %, and nitrate by 25.6, 18.2 and 14.1 %, at depths of 0–30, 30–60 and 60–90 cm, respectively. While ID3 showed higher moisture levels, ID2 provided moisture at FC over growing season. We identified ID2 under M1 with a higher yield (132.6 t ha–1), total biomass (231.1 t ha–1), and irrigation water productivity (6.4 kg m–3) compared to the other IDs as a promising on-farm dripper ID to promote moisture conservation and salinity avoidance. This research also requires studying sugarcane growth under ID2 treatments in different soil textures and irrigation water qualities.
