Uniformity of Water Application under Drip Irrigation in Litchi Plantation and Impact of pH on Its Growth in Partially Reclaimed Alkali Soil

Abstract

A field experiment was conducted to study the effect of varying water application and soil pH on the growth parameters during the establishment of litchi (Litchi chinensis Sonn.) plantation in a partially reclaimed alkali environment. The plant growth parameters such as plant height and girth at collar were studied. Hydraulic performance of drip system was monitored by observing the individual and plant wise emitter discharge. The Christiansen's Coefficient of Uniformity (CCU), Wilcox-Swailes Coefficient of Uniformity (WSCU), Statistical Coefficient of Uniformity (SCU), Low Quarter Distribution Uniformity (SDUIq), and Coefficient for Emitter Flow Variation (CEFV) for the rate of water application were determined. The average value of CCU remained close to 0.63 and 0.75, respectively, on emitters' and plant basis when 4 drippers were employed per plant. Different levels of soil pH as experienced by the litchi plants were grouped into seven soil pH groups viz. less than 7.75, 7.75-8.00, 8.00-8.25, 8.25-8.50, 8.50-8.75, 8.75-9.00 and more than 9.00. In each of the above pH groups, different emitter discharges were observed. The plant wise discharges received in each pH group were further sub-divided and grouped in less than 10, 10-15, 15-20, 20-25, 25-30 and above 30 liter per hour (Ih?¹). The plant growth parameters were significantly different at different soil pH levels. The plant mortality was high and plant height and girth at collar reduced when the soil pH exceeded 8.5. A positive linear trend was observed in growth parameters and the application of discharge at or below a pH level of 8.5, after which the trend was reverse.