| As a new type of fertilizer, organic-inorganic compound fertilizer has been gaining increasing interests in China. In this study, organic-inorganic compound N, P, and K fertilizers were made by combining each of the organic waste materials (including sugar residue, furfural residue, and bio-solids from the production of monosodium glutamate) with urea, ammonium phosphate and potassium sulfate, respectively. The leaching experiments, incubation experiments, and potted plants experiments were conducted to investigate effects of these organic-inorganic compound fertilizers on crop yield, nutrient uptake, nutrient use efficiency, soil fertility, and the cycling of nutrients in soils. The major conclusions are as follows:(1)Organic-inorganic compound fertilizers increased maize grain yield. At the low, medium, and high N application rate, organic-inorganic compound N fertilizer application increased maize grain yield by 19.1%, 9.0% and 5.6%, respectively, compared to the urea treatment. Similarly, compared to inorganic P fertilizer, organic-inorganic compound P fertilizer increased maize grain yield by 19.1%, 11.3% and 37.8%, respectively, at the low, medium, and high P application rate. As with organic-inorganic compound K fertilizer, it also tended to increase maize grain yield compared to inorganic K fertilizer. In the current study, an increase in the ratio of organic material to inorganic components of organic-inorganic compound fertilizer tended to increase crop yield to a limited degree. Given that the same amounts of N were applied, however, organic-N application decreased maize yield relative to inorganic-N treatment.(2)At the same urea N application rate, the relative increase of maize grain yield of the organic-inorganic compound N fertilizer treatment to those of the corresponding organic material treatment was greater than that of the inorganic N fertilizer treatment to no N fertilizer treatment. At the low, medium, and high N application rate, organic-inorganic compound N fertilizer increased maize grain yield by 12.4%, 4.8% and 5.4%, respectively, relative to the urea treatment.(3) Organic-inorganic fertilizers increased nutrients uptake. At the low, medium and high N application rate, organic-inorganic compound N fertilizer increased N uptake of maize plant by 27.9%, 14.6%, and 7.3%, respectively, compared to inorganic N treatment. At the low, medium and fertilizer N application rate, organic-inorganic compound N fertilizer application increased N uptake of maize plant by 29.0%, 21.6%, and 18.9%, respectively, compared to fertilizer N treatment. Similarly, compared to inorganic P treatment, organic-inorganic compound P fertilizer increased P uptake of maize plant by 12.6%, 2.8%, and 33.4%, respectively, at the low, medium, and high P application rate. At the low, medium and high K application rate, organic-inorganic compound K fertilizer increased K uptake of maize plant by 31.3, -9.1, and 16.1%, respectively, compared to K fertilizer treatment.(4) Organic-inorganic fertilizers increased nutrient use efficiency. At the low, medium and N application rate, organic-inorganic compound N fertilizer increased N apparent recovery by 35.4, 13.1, and4.9%, respectively, compared to fertilizer N treatment. However, organic N use efficiency was lower than that of inorganic N when the same amounts of N were applied. In the case of the same amount of urea N applied, organic-inorganic compound N fertilizer application increased N apparent recovery by 11.6-33.5%, compared to urea treatment. At the low, medium and high P application rate, organic-inorganic compound P fertilizer increased P apparent recovery by 16.2, 0.8, and 15.7%, respectively, compared to fertilizer P treatment. Similarly, compared to K fertilizer treatment, organic-inorganic compound K fertilizer increased K apparent recovery by 55.1, -3.3, and 2.1%, respectively, at the low, medium and high K application.(5)Compared with inorganic fertilizer treatment, organic-inorganic compound fertilizer application increased total N concentration in soils and soil available K concentration, whereas it did not impose significant effects on soil organic matter content. In comparison, organic-inorganic compound P fertilizer reduced soil available P concentration compared to inorganic P fertilizer. In addition, organic-inorganic compound fertilizers did not increase soil microbial C and N from a statistical perspective, compared to chemical fertilizers.(6)Compared to chemical P fertilizer, organic-inorganic compound P fertilizer increased the concentrations of soil available P, Ca2-P, and Ca8-P, whereas it reduced soil Al-P concentration.(7) Compared to chemical K fertilizer, organic-inorganic compound K fertilizer containing furfural residue and bio-solid increased the amount of K leached, whereas organic-inorganic compound K fertilizer containing sugar residue decreased the amount of K leached. Also, organic-inorganic compound K fertilizer containing sugar residue and furfural residue increased soil available K concentration, and decreased the amount of K fixed by soil components on the basis of chemical K fertilizer. |
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