Effects of Different Soil Modifiers on Salt Improvement and Distribution, Crop Growth of the Gully Land Consolidation on Loess Plateau

Due to the strong evaporation and leakage loss, secondary saline-alkali was the main problem in the watershed of gully land consolidation on Loess Plateau. Through field farming experiments, five modifiers (maize stalk (MS), humus acid (HA), Yan Ke (YK), He Kang (HK), and nanobiochar (NB)) were studied to investigate the effects of these soil modifiers on soil water and salt distribution, leaf photosynthetic characteristics, and maize growth and yields, as well as economic benefits in secondary saline-alkali soils of gully land consolidation watershed on Loess Plateau in 2019 and 2020. The results showed that soil modifiers could increase the water-holding capacity of the soil, reduce the salt content of the soil profiles, and decompose the accumulation of salt. The maximum desalination rate obtained in 2019 and 2020 increased, respectively, by 71.57% and 46.02%, compared to that in the control treatment. Soil modifiers could increase the net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs), and decreased the intercellular CO2 concentration (Ci). The output increased by 13.63%-31.84%, and revenue increased by 6.48%-38.01%. According to analyzing the production of soil modifier application, we found that the highest net profit was achieved when HK application rate was 52.4 kg/ha. Therefore, this study suggested that 52.4 kg/ha might be recommended as an appropriate soil modifier application strategy to deal with crop growth and improve economic benefit in secondary saline-alkali soils of Northwest China.