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The structures of soil humus (HS) amended with organic wastes (OWs) were closely related to properties of OWs-derived humus-like substances (HSL). This work evaluated the properties of HSL isolated from mushroom residue (MR), chicken manure (CM), sheep manure (SM), tree leaves (TL), maize straw (MS) and fodder grass (FG) and studied the structures of soil humic acid (HA) and fulvic acid (FA) amended with these OW. FTIR results showed that the relative intensities at 1,640 cm−1 peaks of TL-, FG- and SM-derived HAL were higher than other CM-, MS- and MR-derived HAL (p < 0.05), while the 2,930/1,640 ratios were lower (p < 0.05). Relatively lower E4/E6 ratios and ΔlogK values of TL-, FG- and SM-derived HAL were recorded (p < 0.05). Relative intensities at 1,620 cm−1 peaks of soil HA and soil FA amended with TL, FG and SM were higher than other OWs, while the 2,930/1,620 ratios were significantly lower (p < 0.05). The 2,930/1,620 ratio of soil HA and soil FA amended with MS and CM was the highest, respectively. In conclusion, the properties of OWs-derived HSL play important roles in functional groups of soil HS amended with these OWs. [ABSTRACT FROM AUTHOR]

Poor soil fertility conditions limit agricultural production and development in saline-alkali areas. At the same time, in order to solve the problem of environmental pollution caused by agricultural wastes, agricultural wastes are used for organic fertilization of saline-alkali soils. In this study, the amount and structure of soil dissolved organic carbon after the application of different organic wastes was assessed. The results showed that the content of dissolved organic carbon in each component increased significantly (p <.05), while treatment GS recorded the highest content of dissolved organic carbon in each organic carbon component. The UV-visible spectrum of soil dissolved organic carbon recorded different results after the application of organic materials. For water-soluble organic carbon (WSOC), treatment CS was most effective in increasing the molecular weight of soil WSOC while treatment GS was most beneficial in improving the hydrophobicity and aromaticity of soil WSOC. For thermal hydrolyzed organic carbon (THOC), treatment GS was most effective for increasing the molecular weight and hydrophobicity, while treatment SM was most beneficial for increasing aromaticity. For hydrochloric acid and hydrolyzed organic carbon (HHOC), treatment SM was most effective in increasing molecular weight, while treatment FG and GS were most beneficial in improving the hydrophobicity and aromaticity of HHOC. For Alkali hydrolysis of organic carbon (AHOC), treatment GS was most beneficial for increasing the molecular weight, aromaticity, and hydrophobicity of AHOC. Amongst all the treatments the organic material treatments increased the aromaticity, hydrophobicity, molecular weight, and humification degree of soil soluble organic carbon compared with CK. [ABSTRACT FROM AUTHOR]

Soil available nutrients and soil salt ions are considered to play a significant role in soil fertility. A two-year field experiment was conducted to investigate the effects of different agricultural organic wastes on soil available nutrients and soil ions in a primary saline soil, located in the west of Jilin Province, China. The treatments were granular corn straw (GS), coarse corn straw (CS), sheep manure (SM), fodder grass (FG), and control (CK). The results showed that agricultural organic wastes effectively decreased soil pH by 1.28%-3.83%. The application of agricultural organic wastes also improved soil available nutrients, of which the available nitrogen (AN) increased by 23.64%-32.54%, the available phosphorus (AP) increased by 16% −19.93%, and the available potassium (AK) increased by 2.78% – 8.42%. In contrast, the content of soil salt ions decreased significantly with the exception of potassium ions. Linear dependence suggests that, with the decrease of soil pH, the soil available nutrient content was higher. From the correlation analysis, the relationship between other salt ions and soil available nutrients showed an extremely significant negative correlation with the exception of potassium (K+). The redundancy analysis (RDA) showed that calcium (Ca2+) and potassium (K+) are the main factor affecting soil available nutrient content in 2a (about 12 months after organic wastes were applied) and 3a (about 24 months after organic wastes were applied), respectively. In conclusion, treatment GS is recommended for improving soil available nutrients and decreasing the pH and content of soil salt ions in primary saline-alkali soils. CK: control without orgaanic material; GS: granular corn straw; CS: coarse corn straw; SM: sheep manure; FG: fodder grass; AN: available nitrogen; AP: available phosphorus; AK: available potassium; RDA: redundancy analysis; 1a: before the application of organic wastes; 2a: about 12 months after organic wastes were applied (first year); 3a: about 24 months after organic wastes were applied (second year). [ABSTRACT FROM AUTHOR]

Poor soil has restricted the crop production in semiarid soil. Fulvic acid (FA) is considered to play an significant role in soil fertility. The amount and structure of FA after application of different organic wastes (OWs) was assessed in this work. Six treatments were involved in this experiment: chemical fertilizer combined with chicken manure (CM), sheep manure (SM), maize straw (MS), fodder grass (FG), and tree leaves (TL), while chemical fertilizer only was used as control (CK). The soil FA content (P < 0.05) after the application of TL was the highest than other OWs. The E 4 /E 6 ratios, Δlog K values, aliphatic C/aromatic C ratios of soil FA after the application of TL were the lowest than other OWs, whereas the C/H ratio was the highest. The specific fluorescence intensities (SFI) of peak A (Ex/Em 260–265/415-430 nm) and peak B (Ex/Em 310–315/415-430 nm) from EEM fluorescence spectrum of FA were the lowest after the application of TL. In conclusion, the application of TL was the most effective for improving FA accumulation, and making FA complex and stability. Thus, TL is the recommended OW for use in semiarid soil under plastic mulched drip irrigation conditions. The soil FA content after application of TL was the highest. • The application of TL could make the structure of FA complex and stability, and improve storage of soil organic matter. • The application of CM could make the structure of FA simple and improve the updating of FA. • TL would be used as the most suitable OW type in semiarid soil under plastic mulched drip irrigation conditions. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the variation in labile organic carbon fractions after the application of organic wastes (OWs) in semiarid soil under plastic mulched drip irrigation. The two-year experiment involved six treatments: chicken manure (CM), sheep manure (SM), mushroom residue (MR), maize straw (MS), fodder grass (FG), and tree leaves (TL), with an unamended soil (no OWs) as control. In 2015 and 2016, treatment with OWs led to increased levels of soil organic carbon (SOC), dissolved organic carbon, microbial biomass carbon, easily oxidized organic carbon, as well as higher carbon management indexes and yields and lower oxidation stability coefficients. Higher SOC contents (p <0.01) were achieved in both years for TL and MS compared to the other OWs. In particular, the SOC content in 2016 was higher (p <0.05) for TL than MS. Compared to the other OWs, the easily oxidized organic carbon levels and carbon management indexes in both years were higher (p <0.01) for CM, SM, and MS, whereas the oxidation stability coefficients were lower (p <0.01). In conclusion, among the studied treatments, the application of MS was the most effective for improving soil fertility and enhancing soil carbon sequestration. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the variation in the amount and structure of humic acid (HA) after the application of organic wastes (OWs) in semiarid soil under plastic mulched drip irrigation, measured by elemental composition, excitation-emission matrix (EEM) fluorescence, and carbon 13 nuclear magnetic resonance ( 13 C CPMAS NMR). The experiment involved chemical fertilizer combined with chicken manure (CM), sheep manure (SM), maize straw (MS), fodder grass (FG), and tree leaves (TL), while chemical fertilizer only was used as control (CK). The highest cation exchange capacity (CEC), soil organic carbon (SOC), and HA contents ( P < 0.05) were achieved for TL compared to other OWs. The E 4 /E 6 ratio, Δlog K value, and the aliphatic C/aromatic C ratio of HA were the lowest for TL treatment than for other OW treatments, whereas the highest C/H ratio was obtained. The specific fluorescence intensities (SFI) of peak A (330–370/460-490 nm), peak B (450–465/515-525 nm), and peak C (255–270/465-490 nm) mainly referred to humic acid component from EEM fluorescence spectrum of HA were lower for TL compared to other OWs. In conclusion, the application of TL was the most effective for improving the accumulation of SOC and HA, and making the structure of HA complex and stability. Thus, TL is the recommended OW for use in semiarid soil under plastic mulched drip irrigation conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In searching for the optimum method for amelioration of solid organic waste by remedying black soil and tackling rainfall changes, effects of water conditions and solid organic wastes are studied on particulate organic carbon (POC) structure by 13C‐NMR spectroscopic analysis in a 3‐year split‐plot experiment. Experimental plots are under natural rainfall, water deficit, and excess water with single chemical fertilizer, cow manure, chicken manure, crop, or plant residue treatments. The results reveal that solid organic wastes have the potential to improve POC stability. Under natural rainfall conditions, the degressive order by the POC stability is plant residue, crop residue, cow manure, and then chicken manure; under water deficit, it is plant residue, crop residue, chicken manure, and then cow manure; under excess water conditions, it is plant residue, cow manure, chicken manure, and then crop residue. The interchange between aromatic carbon and alkyl or alkoxy carbon gives a remarkable reflection of the effect of water on POC structure. The plant residue increases the aromatic carbon at rates of 4.6, 6.4, and 9.3% under natural rainfall, water deficit, and excess water conditions, respectively. Studying the three water conditions, it could be shown that under a water deficit or excess water condition, both chicken manure and crop residues are unfavorable to POC stability; cow manure is conducive to POC stability only under excess water condition. Leaves, therefore, serve as the optimum amelioration material. [ABSTRACT FROM AUTHOR]