Impacts Of Different Organic Fertilizers On Carbon, Nitrogen And Phosphorus Concentrations In A Purple Soil

The soybean and rice pot experiments were done to study the changes of carbon, nitrogen and phosphorus of the arid purple soil and the paddy purple soil by applying the humic acid and chitin organic fertilizers. The results showed: 1. Impacts of humic acid and chitin on the chemical properties of dryland soil for potted soybean plant cultivation(1) Impacts of different organic fertilizers on the available nutrient concentrations in purple soils The alkaline hydrolysable-nitrogen(AH-N) concentrations of soil treated with humic acid and chitin were higher than that of non-fertilized soil during germination and flowering. But during sprouting and podding, the AH-N concentrations of treated soil were lower than that of non-fertilized soil. For most of the reproductive period, the available phosphorus(AP) concentrations of soil treated with humic acid and chitin were lower than that of non-fertilized soil. And the available potassium(AK) concentration of soil treated with humic acid was higher than that of non-fertilized soil from germination to podding, and the AK concentration of soil treated with chitin was also higher than that of non-fertilized soil during flowering and sprouting.(2) Impacts of different organic fertilizers on the p H values of purple soils Except for the podding stage of the humic acid group and the germination stage of the chitin group, the application of both humic acid and chitin lowered the soil’s p H values throughout the soybean plants’ lifespan compared with that of non-fertilized group.(3) Impacts of different organic fertilizers on the dissolved organic matter concentrations in purple soils Except for the podding stage of the humic acid group, the application of both humic acid and chitin raised the soil’s dissolved organic carbon(DOC) concentrations from germination to podding compared with that of non-fertilized group. Except for the sprouting stage, the dissolved organic nitrogen(DON) concentrations of soil treated with humic acid and chitin were lower than that of non-fertilized soil from germination to podding. Except for the sprouting stage of the humic acid group, the application of humic acid and chitin raised the soil’s dissolved organic phosphorus(DOP) concentrations from germination to podding compared with that of non-fertilized group.(4) Impacts of different organic fertilizers on the nitrate-nitrogen(nit N) and ammonia-nitrogen(amm N) concentrations in purple soils Throughout the soybean plants’ lifespan, the application of humic acid and chitin raised the soil’s nit N concentrations compared with that of non-fertilized group. But only the amm N concentration of soil treated with humic acid was significantly higher than that of non-fertilized soil from germination to sprouting. The concentration was 506.90%-527.80% higher.(5) Correlational analysis of the different chemical components in purple soils during the soybean plants’ reproductive period For the non-fertilized group of soybean cultivation, no significant correlations were observed among the soil’s concentrations of nit N, amm N, DOC, DON, DOP, AP, AK and AH-N, as well as the p H values(p>0.05). For the humic acid group, positive correlations were observed between the soil’s amm N and DOC concentrations, and between AP and DON concentrations; a negative correlation was observed between amm N and AP concentrations. These correlations were significant(p<0.05). For the chitin group, only one positive correlation was observed between DOC and AP concentrations and the correlation was significant(p<0.05). 2. Impacts of humic acid and chitin organic fertilizers on the chemical properties in the paddy soil of rices(1) Impacts of different organic fertilizers on the available nutrient concentrations in purple soils Except for the flowering stage of the humic acid group and the tillering and flowering stages of the chitin group, the application of humic acid and chitin raised the soil’s AH-N concentrations from the rice’s tillering to ripening compared with thenon-fertilized group. Except for the tillering stage of the humic acid group and the jointing stage of the chitin group, the application of humic acid and chitin lowered the soil’s AP concentrations from tillering to ripening, compared with the non-fertilized group. With the exception of ripening, from tillering to grain-filling, the application of humic acid and chitin lowered the soil’s AK concentrations compared with the non-fertilized group.(2) Impacts of different organic fertilizers on the p H values of purple soils Compared with the non-fertilized group, the application of humic acid and chitin raised the soil’s p H values during tillering and flowering, and lowered the soil’s p H values during jointing and grain-filling.(3) Impacts of different organic fertilizers on the dissolved organic matter concentrations in purple soils Compared with the non-fertilized group, the application of humic acid and chitin lowered the soil’s DOC concentrations. The application raised the DON concentrations from tillering to jointing and lowered the concentrations from grain-filling to ripening. From jointing to ripening, such fertilizer application raised the soil’s DOP concentrations.(4) Impacts of different organic fertilizers on the nit N and amm N concentrations in purple soils Except for the grain-filling stage of the humic acid group and the ripening stage of the chitin group, the application of humic acid and chitin lowered the nit N concentrations compared with that of the non-fertilized group from tillering to ripening. Except for the flowering stage of the humic acid group and the tillering and grain-filling stage of the chitin group, the application of humic acid and chitin lowered the soil’s amm N concentrations from tillering to ripening.(5) Correlational analysis of the different chemical components in purple soils For the non-fertilized group of rice cultivation, only two negative correlations were observed between DOC and AK concentrations and between the DON and nit N concentrations. These correlations were significant(p<0.05). For the humic acid group, only one negative correlation was observed between DON and nit N concentrations and one positive correlation between DOC and AH-N concentrations. These correlations were significant(p<0.05). For the chitin group, positive correlations were observed between DON and AP concentrations and DOC and DOP concentrations. These correlations were also significant(p<0.05).