Effects Of Ash-based Compound Fertilizer On Soil Labile Organic Carbons

Recycling of waste and animal manure fertilizer technology has become the important means for energy-saving and emission reduction and the improvement of ecological environment. In this paper, field experiment was conducted. No fertilizer (CK), chemical fertilizer only (NPK), three kind of ash-based inorganic compound fertilizers and three kind of ash-based organic-inorganic compound fertilizers, including high, medium and low level were investigated. The dynamics of soil readily oxidizable organic carbon(ROC), water-soluble organic carbon(WSOC), dissolved organic carbon(DOC), correlations with total organic carbon(TOC) were studied under the influences of different compound fertilizer on wheat-maize system. The major conclusions were as follows.(1) The ROC content were significantly improved under ash-based compound fertilizers. And they presented maximum at booting stage. At 0-20 cm soil layer, the ROC content increased 3.25-5.00% under ash-based inorganic compound fertilizers and 5.63-6.92% under ash-based organic-inorganic compound fertilizers.After one year, the ROC content under ash-based organic-inorganic compound fertilizers significantly higher than that under ash-based inorganic compound fertilizers, and they both significantly higher than CK and NPK (P<0.05). The ROC content at 20～40 cm and 40-60 soil layer were lower than 0-20 cm. The content increased lower, too.But the changing trends were similar.(2) The DOC content were significantly improved under ash-based compound fertilizers. And they presented maximum at jointing stage. At 0～20 cm soil layer, the DOC content decreased -5.42-3.01% under ash-based inorganic compound fertilizers and increased 7.81-19.47% under ash-based organic-inorganic compound fertilizers.However, it decreased 10.95% under NPK and 18.86% under CK.After one year, the DOC content under ash-based organic-inorganic compound fertilizers significantly higher than that under ash-based inorganic compound fertilizers, and they both significantly higher than CK and NPK (P<0.05). The DOC content at 20～40 cm and 40-60 soil layer were lower than 0-20 cm. The content increased lower, too.But the changing trends were similar.(3) The WSOC content were significantly improved under ash-based compound fertilizers. The changing trend was similar with DOC. And they presented maximum at jointing stage, too. At 0-20 cm soil layer, the WSOC content decreased 17.03-23.20% under ash-based inorganic compound fertilizers and increased-3.00-4.28% under ash-based organic-inorganic compound fertilizers.However, it decreased 26.71% under NPK and 41.34% under CK. After one year, the WSOC content under ash-based organic-inorganic compound fertilizers significantly higher than that under ash-based inorganic compound fertilizers, and they both significantly higher than CK and NPK (P<0.05). The WSOC content at 20～40 cm and 40～60 soil layer were lower than 0-20 cm. The content increased lower, too.But the changing trends were similar.(4) With the deepening of soil layer and the passing of time, the correlation coefficient became greater between soil organic carbon indexes. ROC was the most sensitive indicators among these three variability indicators of organic carbon under ash-based compound fertilizers. And the correlation coefficient between ROC and TOC was 0.977, which was the maximum.DOC and WSOC showed such significant correlation that could predict trends reciprocally. The maximum correlation coefficient between them was 0.972.