红壤区旱地和水田土壤磷素状况及其流失风险

红壤一般偏酸且铁铝富集,磷与铁、铝形成Fe-P、Al-P,降低了红壤磷的有效性.施磷提高红壤供磷能力,但是未被作物利用的磷积累在土壤中,对水体环境构成威胁.研究红壤磷素状况对于提高作物产量和保护环境具有重要意义.已有很多关于红壤磷素状况方面的报道,但是很少将红壤磷素状况与水体磷进行关联分析.在典型红壤区江西省余江县布点...

Current phosphorus status of red soil in drylands and paddy fields and its loss risks

Red soils are generally acid and contain more Fe and Al that can form Fe-P and Al-P,resulting in low P bioavailability.Applying P fertilizer can improve the capability of red soils to supply P for plants,but the P that is not used by plants accumulates in soils and has potential risks in polluting surface water.Researching soil P status has important implications for increasing crop yield and protecting ecological environment.Much more attention has been paid to the P status of red soils and surface water,but fewer studies pay attention to the direct link between red soil P status and surface water P pollution.We collected 54 soil samples in drylands,54 soil samples in paddy fields and 24 water samples around paddy fields in Yujiang County,Jiangxi Province.We determined the Olsen-P,Bray-P and CaCl2-P concentrations of soil samples,and the total P concentrations of water samples.The results showed that,according to Olsen-P,11%of drylands and 39%of paddy fields were P-deficient,61%of drylands and 39%of paddy fields were P-moderate,and 11%of drylands and 11%of paddy fields were P-excess.According to Bray-P,11%of drylands and 33%of paddy fields were P-deficient,6%of drylands and 33%of paddy fields were P-moderate,and 77%of drylands and 6%of paddy fields were P-excess.A extremely correlation was observed among Olsen-P、Bray-P and CaCl2-P.On the basis of the regressive analyses between Olsen-P and CaCl2-P,and between Bray-P and CaCl2-P,the change points of P loss were 56.31 and 118.4 mg·kg^-1 for Olsen-P and Bray-P,respectively.According to the change points,the concentrations of Olsen-P and Bray-P in paddy fields never exceeded the P change point,but 50%and 33%of drylands exceeded the P change points of Olsen-P and Bray-P,respectively.The total P concentrations in the ditches around paddy fields never exceeded the total P standard for surface water in class II of the Environmental Quality Standard for Surface Water.Taken together,dryland soils have high available P concentrations and high P loss risk,whereas paddy soils have low available P concentrations and low P loss risk.