Effects of Long-term Site-specific Fertilization on Soil Physical and Chemical Properties and Nutrients in Dry Farmland

In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farmland, the soil p H, total salt content,crop root length, root weight, soil organic matter, available nitrogen, total nitrogen, total phosphorous and total potassium in different fertilization treatments were measured from 2010 to 2016. Multiple comparisons of the data were performed using Duncan's new multiple range test. The results indicated that in the 0-20 cm soil layer, soil p H value and total salt content changed in different patterns, and varied greatly from 2010 to 2016(P<0.05). The changes of both root length and root weight of millet over time fitted S-shaped curves. The root length and root weight in the four fertilization treatments(Treatment 2 to Treatment5) increased faster than those in the control(Treatment 1). The soil organic matter content in all the five treatments gradually increased from 2010 to 2016. The content of alkaline hydrolyzable nitrogen in soil rapidly increased in the first two to three years of the experiment, followed by a slow increase or decrease in 2013, and then raised rapidly again from 2014 to 2016.The soil total nitrogen content varied significantly from 2010 to 2016. The total phosphorus content in soil changed in a different pattern from that of total nitrogen content. The seven-year field trails revealed that soil p H, total salt content, root length, root weight and soil nutrient all changed with the increase of fertilizer level, and that long-term fertilization is of significance for maintaining soil fertility, improving soil quality and reducing soil salinization.

Effects of Irrigation Amount on Soil Water Content of Gentiana macrophylla

[Objectives]This study was conducted to investigate the effects of different irrigation quotas and irrigation times on soil physical and chemical properties and water content in the planting areas of Gentiana macrophylla in dry farming areas of southern Ningxia.[Methods]G.macrophylla planted for three years was selected as the experimental material,and the water content,nutrients,bulk density and total porosity of the soil at different depths(0-20 and 20-40 cm)were measured under different irrigation quotas and irrigation times.[Results]Compared with the CK,different irrigation quotas and irrigation times could significantly improve the water contents of the 0-20 and 20-40 cm layers in the planting areas of G.macrophylla.The change trend of water content at the 0-20 cm soil depth was 3 times of irrigation>2 times of irrigation>1 time of irrigation>CK,and that at the 20-40 cm soil depth was 2 times of irrigation>3 times of irrigation>1 time of irrigation>CK.With the increase of irrigation times,soil urease in the 0-20 cm soil showed a trend of decreasing at first and then increasing,reaching a maximum value of 0.415 mg/g·24 h with 1 time of irrigation,which increased by 84.44%compared with the CK,and the value with two times of irrigation was basically the same as that of the CK,but 3 times of irrigation resulted in a value 57.33%higher than the CK.However,the changes of 20-40 cm were the opposite.The change trends of alkali-hydrolyzable nitrogen in the 0-20 and 20-40 cm soil layers with irrigation times was smaller,and the contents of soil organic carbon,available phosphorus and available potassium increased first and then decreased with the increase of irrigation times,and were generally higher than those in the CK.[Conclusions]This study provides a theoretical and technical basis for the artificial cultivation of G.macrophylla in dry farming areas of Ningxia.