Water availability is the primary limiting factor for vegetation restoration and agricultural production in the arid and semi-arid regions of the Loess Plateau. The application of soil amendments is an effective approach for enhancing soil water use efficiency (WUE) in this area. The clay mineral of attapulgite (ATP) is a highly promising soil amendment due to its hydrophilic properties and adsorption capacity, which could improve soil water availability. In this study, we selected two soil types (dark loess soil and loess soil) with distinct soil textures from the Loess Plateau, and conducted an experiment with three levels of ATP application (0, 20, and 40 g·kg-1) and three water management strategies (drought stress group, drought-rewatering cycle group, and normal water condition group), resulting in a total of 18 experimental treatments. We measured photosynthetic parameters and WUE of maize, and investigated the impact of ATP on soil water availability. The results showed that across the entire growing season, both drought stress group and drought-rewatering cycle group significantly enhanced WUE. Additionally, the ATP-amended treatments exhibited significantly higher WUE compared to the non-amended treatments. The photosynthetic parameters of maize under different treatments all exhibited threshold response patterns based on change in soil relative water content (RWC). Both Pn and WUE increased with rising RWC but decreased after exceeding the critical threshold value corresponding to each treatment. At the maximum ATP application rate (40 g·kg-1), the WUE of dark loess soil and loess soil reached their peaks at RWC of 73.7% and 98.3%, respectively. With Pn and WUE as indicators of "productivity" and "efficiency" of maize production, the application of ATP enabled the achievement of high yield and efficiency even at the lower soil water conditions in loess soil. The application of ATP demonstrated superior efficacy in enhancing soil water availability in loess soil compared to dark loess soil.
水分有效性是黄土高原干旱与半干旱地区植被恢复和农业生产的主要限制因素,添加土壤改良剂是提高该区域土壤水分利用效率的有效途经。凹凸棒土(ATP)是一种极具潜力的土壤改良剂,其亲水性和吸附性可有效改善土壤水分有效性。本研究选取黄土高原地区两种不同质地典型土壤(黑垆土和黄绵土),设置3个ATP添加量(0、20和40 g·kg-1)及3种水分调控模式(水分胁迫、干旱-复水和正常水分调控模式),共18个处理,通过盆栽试验测定玉米植株光合参数和水分利用效率(WUE),探究ATP对土壤水分有效性的影响。结果表明: 在整个玉米生育期内,不同水分调控模式中水分胁迫和干旱-复水模式WUE较正常水分调控模式高;添加ATP处理WUE均高于未添加处理。不同处理玉米光合参数基于土壤相对含水量(RWC)的变化均出现阈值响应规律,净光合速率(Pn)、WUE随RWC的增加而增加,超过各处理对应临界值后减小。在ATP添加量高(40 g·kg-1)时,黄绵土和黑垆土WUE分别在RWC为73.7%和98.3%时达到最高值。以Pn和WUE分别表征“产”和“效”水平,黄绵土ATP处理维持高产高效对应的RWC(57.9%～90.2%)低于未添加处理(63.0%～90.3%),但黑垆土ATP处理维持高产高效对应的RWC(59.7%～86.1%)高于未添加处理(51.7%～83.8%),故黄绵土添加ATP处理可在较低土壤水分条件下实现高产高效。在提升土壤水分有效性方面,黄绵土施加ATP的效果优于黑垆土。.
Keywords: Loess Plateau; photosynthetic property; water use efficiency.