Water–Nitrogen Coupling Effect on Drip-Irrigated Dense Planting of Dwarf Jujube in an Extremely Arid Area

Abstract

Hami, Xinjiang, is located in an extremely arid region and jujube is the main economic crop. It is important to adopt dwarf and close-planting technology under drip irrigation and to optimize water and fertilizer management to improve jujube yield and quality. Local 12-year-old jujube trees were treated using two factors of irrigation and fertilization. Three irrigation amounts (520, 700, and 880 mm) and three fertilization levels (248, 318, and 388 kg/hm2) were set up in plot experiments. The root system, yield, and quality of jujube were monitored under different irrigation and nitrogen application combinations. The effects on water use efficiency (WUE), nitrogen partial factor productivity (PNP), and economic benefit were analyzed. The water and fertilizer coupling effect of dwarf closely planted jujube was studied by combining multiple regression and spatial analyses. The yield, quality, economic benefits, WUE, and PNP of jujube were significantly affected by irrigation and fertilization. Multiple regression and spatial analyses showed that the highest yield was for irrigation of 700 mm and a nitrogen rate of 340 kg/hm2. For the maximum net benefit, irrigation was 806 mm and nitrogen was 388 kg/hm2; correspondingly, for the highest total sugar, values were 688 mm and 362 kg/hm2; for vitamin C, they were 622 mm and 376 kg/hm2; for PNP, they were 880 mm and 256.57 kg/hm2; and for WUE, they were 520 mm and 388 kg/hm2. A comprehensive evaluation of each index showed that the acceptable irrigation amount for yield, quality, WUE, and net benefit of ≥85% of the maximum value was 600–628 mm, and the nitrogen application rate was 360–372 kg/hm2. This study provides guidance for the scientific management of water and fertilizer in the drip irrigation and fertilization process of local jujube trees.

Water–Nitrogen Coupling and Multi-Objective Optimization of Cotton under Mulched Drip Irrigation in Arid Northwest China

“…Lin et al established a functional relationship between water and nitrogen input and jujube yield, fruit quality, and economic benefit in an extremely arid area using quadratic regression. Through spatial analysis, the multi-objective of suitable water and nitrogen interval for comprehensive yield, fruit quality, and economic benefit was obtained [10]. However, there is still a shortage of water and nitrogen management methods for cotton based on multi-objective optimization such as WUE, NUE, yield, and income.…”

Effect of Microsprinkler Irrigation and Nutrient Management on Growth, Yield, Water Use Efficiency and Macronutrient Accumulation of Large Cardamom in Sub-Himalayan Region of India

“…The seasonal water use for large cardamom during the whole growing period was computed using the following one-dimensional field water balance equation (Lin et al 2019):…”

Promoting the production of salinized cotton field by optimizing water and nitrogen use efficiency under drip irrigation

“…Soil moisture was measured by soil drying method, and average value was taken. Due to the depth of groundwater, flat terrain and low rainfall, U, R and D were ignored during growth period (Lin et al, 2019).…”

“…In this paper, using spatial analysis (Thompson and Doerge, 1996;Lin et al, 2019), we carried out the horizontal projection of three-dimensional surface obtained by multiple regression equation of each index to find the overlap of acceptable regions of each target (≥85% maximum) and obtained the optimal combination range of each index. Based on multiple regression analysis of cotton growth indices under drip irrigation and different salt stress, this paper aimed to (1) comprehensively evaluate the yield, quality, water-saving, fertilizer saving and high efficiency of cotton combined with spatial analysis method; (2) propose an optimal water-nitrogen coupling model for the above indices; and (3) reveal the response of cotton growth to water and nitrogen regulation under salt stress.…”