Abstract
High salinity and low fertility have restricted crop production in primary saline-alkali soils. Soil organic carbon (SOC) and surface charge characteristics affect the soil fertility and soil colloid characteristics of primary saline-alkali soils, respectively. In this paper, the SOC and surface charge properties of primary saline-alkaline soil under organic wastes applications were assessed. Five treatments were involved in this experiment: chemical fertilizer combined with sheep manure (SM), corn straw (CS), fodder grass (FG), and granular corn straw (GS), while chemical fertilizer only was used as control (CK). The content of SOC was significantly different under different organic wastes application (p < 0.05). Treatment GS recorded the highest content of SOC compared with the other treatments. In addition, the content of each SOC density fraction increased after the application of organic wastes. Similarly, the application of organic wastes, increased the proportion of organic carbon in free light fraction (Fr-FLOC) and organic carbon in occluded fraction (Oc-FLOC) in the soil however the proportion of organic carbon in heavy fraction (HFOC) decreased. In this study, we found that treatment GS has a greater impact on soil surface charge properties than other treatments, and through redundancy analysis (RDA) the content of SOC and Fr-LFOC (F = 24.704, p = 0.004; F = 19.594, p = 0.002) were identified as the main factors affecting the surface charge properties of soil organic carbon. In conclusion, GS is the recommended organic waste for ameliorating primary saline-alkali soil, as compared to the other organic waste treatments.
Highlights
The saline-alkali land in the Songnen Plain of Northeast China is 300 × 104 hm2 [1], which is one of the three major areas of soda saline soil distribution in the world [2]
The content of Soil organic carbon (SOC) in the different treatments was ranked as follows: granular corn straw (GS)>sheep manure (SM)>corn straw (CS)>fodder grass (FG)>CK, whereby the content of SOC of treatment GS increased by 151.69%, compared with CK (p < 0.05) (Table 3) and was higher than the other organic waste treatments
Our study found that treatment GS had a greater impact on soil surface charge properties compared with the other treatments (Tables 4 and 5), which is related to the different rates of decomposition of various organic wastes in the soil
Summary
The saline-alkali land in the Songnen Plain of Northeast China is 300 × 104 hm2 [1], which is one of the three major areas of soda saline soil distribution in the world [2]. The ecological environment of the saline-alkali land in the Songnen Plain of Northeast China is fragile and it is one of the most serious desertification areas in northern China [3]. In order to solve this series of problems, many studies have proposed using agricultural organic waste as a soil fertilizer. This is because the application of agricultural organic waste has proven to be an efficient way of improving the fertility and quality of saline-alkali soil [7,8,9]
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