Effects of planting patterns and irrigation quotas on alkalized solonchak and growth of amorpha

Saline-alkali soil is a general name referring to saline soil, alkaline earth salt and other saline and solonetzic soils. Accumulation of soluble salts in the proximity of the surface of saline-alkali soil could result in salt stress impeding crop growth as a result. Soil salinity is a limiting factor in agricultural production and an environment concern not only in China but worldwide. Gansu province in Chinahas a type of alkalized solonchak, a special saline soil characterized by high salt contentand poor soil structure which combined to impend crop growth. The purpose of this paper is to experimentally investigate the impact of planting patterns and irrigation amounts on soil salinity and plant growth in the alkalized solonchak. The experiment was conducted at Jingyuan in Gansu province (37°02' N, 104°96' E) using amorpha (Amorpha fruticosa L.) grown in the alkalized solonchak as the model plant. Prior to the experiment, desulfurized gypsum was applied to the soil at 18 t/hm2. We compared two planting pattern: furrow planting and non-furrow planting, and three irrigation amounts: 8 250, 9 750, 11 250 m3/hm2, each treatment having three replicas. The results show that: 1) All treatments significantly reduced soil pH, alkalinity and salt content, and there was no significant difference in pH and alkalinity between the treatments. Saltcontent in top 0-40 cm soil under furrow planting decreased by 15.7% compared to that under non-furrow planting. 2) Under furrow planting, the irrigation and precipitation accumulated in the furrow ditch, thereby improving soil moisture and reducing soil salinity, compared that under non-furrow planting. Furrow planning improved survival rate, preservation rate, height, base diameter and crown width of the amorpha, compared to non-furrow planting. 3) There was no significant difference in growth index of the amorpha between the irrigation 9 750 and 11 250 m3/hm2, indicting excessive irrigation not only wasted water but also increased the risk of secondary salinization. Using raised-bed cultivation with the amorpha planted in the furrow, along with applying 18 t/hm2 of desulfurized gypsumand irrigating 9 750 m3/hm2 of water was most suitable for improving plant growth in the alkalized solonchak in Gansu province. The results have wide application for developing sustainable agriculture inthe alkalized solonchak in Gansu and other regions.