不同类型有机物料的有机磷组成及生物有效性

  【目的】  研究不同有机物料的有机磷组成及其作为磷源施用后的供磷能力，为化肥磷的有机替代奠定理论基础。  【方法】  供试有机物料包括粪肥类 (猪粪、羊粪)、绿肥类 (豌豆、苜蓿和绿豆)、秸秆类 (小麦秸秆、玉米秸秆和油菜秸秆)。分析了8种有机物料的全磷、有机磷含量和C/P值，采用Bowman-Cole方法测定了有机磷中的活性 (LOP)、中活性 (MLOP)、中稳性 (MROP) 和高稳性有机磷 (HROP) 4个组分的含量。用供试的8种有机物料进行了小麦盆栽试验，分析了土壤速效磷含量、小麦吸磷量与不同有机物料的有机磷组成、碳/磷 (C/P) 值之间的关系。  【结果】  粪肥、绿肥和秸秆中的全磷含量分别为5.49～5.52、1.19～2.59、0.57～1.07 g/kg，有机物料中有机磷含量占全磷的比例在31.3%～55.2%，除绿豆秸秆外，有机磷含量小于无机磷。有机磷中LOP、MLOP、MROP和HROP的平均比例分别为8.5%、45.2%、41.5%和4.9%。LOP平均含量以粪肥类 (175.5 mg/kg) > 绿肥类 (67.03 mg/kg) > 秸秆类 (25.8 mg/kg)；以猪粪、绿豆秸秆的MLOP含量相对较高；MROP含量羊粪 > 猪粪 > 苜蓿秸秆 > 绿豆秸秆 > 豌豆秸秆 > 玉米秸秆 > 油菜秸秆 > 小麦秸秆；HROP在粪肥中的含量显著高于其他类型物料。施用绿肥和粪肥显著增加了小麦的吸磷量和生物学产量，而施用秸秆则不同程度降低了小麦的吸磷量和生物学产量。小麦吸磷量与土壤速效磷含量呈线性正相关关系，与有机物料C/P值呈极显著负相关关系，与LOP、MLOP、MROP呈极显著正相关关系，与HROP相关性不显著；土壤速效磷与有机物料C/P值呈负相关关系。  【结论】  供试有机物料中的全磷含量以粪肥类 > 绿肥类 > 秸秆类，无机磷含量均大于有机磷含量 (绿豆秸秆除外)，有机磷以中活性和中稳性有机磷为主。绿肥类和粪肥类物料中含磷量高、且C/P值较低，作为肥料使用能显著增加土壤速效磷含量、小麦生物学产量和吸磷量，可以有效替代一定比例的磷肥。而秸秆类有机物料含磷量较低，且C/P值较高，不适宜作为化肥磷的有机替代物料。

The composition of organic phosphorus and bioavailability of different organic materials

Objectives]This study investigated the organic P composition of different organic materials and their P supply capacity as P sources,providing theoretical and data reference for the organic substitutions of P fertilizer.Methods]A wheat pot experiment was carried out,the used organic materials included manures(pig manure,sheep manure),legumes(pea,alfalfa,mung bean),straws(wheat straw,maize straw,rape straw).The total and organic P contents and the C/P ratio in the eight materials were analyzed,and the organic P was fractioned into labile organic P(LOP),medium-labile organic P(MLOP),medium-stable organic P(MROP)and high-stable organic P(HROP)via the Bowman and Cole methods.The wheat P uptake,soil available P content were determined.Results]The total P content in manures,legumes and straws were 5.49–5.52 g/kg,1.19–2.59 g/kg and 0.57–1.07 g/kg respectively,the proportion of organic P was in range of 31.3%–55.2%.Except mung bean stalks,the organic P contents in all the tested organic materials were lower than inorganic P contents.In the total organic P,the average proportions of LOP,MLOP,MROP,HROP were 8.5%,45.2%,41.5%and 4.9%,respectively.The LOP content was in the order of manures(175.5 mg/kg)>legumes(67.03 mg/kg)>straws(25.8 mg/kg).The MLOP contents were relatively high in pig manure and mung bean straw.The MROP content was significantly different and in order of sheep manure>pig manure>alfalfa>mung bean>pea>maize straw>rape straw>wheat straw;The HROP content in manures was significantly higher than that in the other organic materials.The application of legumes and manures significantly increased the P uptake and biological yield of wheat,but application of straws significantly reduced them.The P uptake of wheat was positively correlated with soil available P content,negatively correlated with the C/P ratio of organic materials,and positively correlated with the LOP,MLOP and MROP of organic materials,not correlated with HROP contents.The content of soil available P was negatively correlated with the C/P of organic materials.Conclusions]In all the tested organic materials in this experiment,the total P content is in order of manures>legumes>straws,and the organic P content is lower than inorganic P,except mung bean stalks.Medium liable and medium stable P(MLOP and MROP)are the two main fractions in the organic P.Legumes and manures have relatively high P content and relatively low C/P ratio,their application could increase soil available P,so can be used to replace a certain ratio of chemical P fertilizer.While straws have low P content and high C/P ratio,so the bioavailability of P is low,not suitable for use as part of P fertilizer.