【作者】 高静；

【导师】 徐明岗；

【作者基本信息】 中国农业科学院 ， 土壤学， 2009， 博士

【摘要】 磷素是植物生长的必需元素,但由于磷素易固定在土壤中,磷肥的利用率较低。因此,阐明长期施肥下土壤磷库的演变特征,提高磷肥的利用效率是我国农业科学中一个重要的问题,对于生态环境保护和农业可持续发展,均具有重要的理论意义和实践价值。本论文统计分析了长期施肥条件下不同轮作方式我国16个典型农田土壤磷库(土壤全磷、有效磷、磷盈亏速率)及作物磷肥效率(作物吸磷量、磷肥回收率、磷肥利用率、磷肥农学效率、磷肥生理效)的时空演变特征及其影响因素。本论文包括9个施肥处理,即不施肥(CK)、单施化肥氮(N)、施用氮、钾化肥(NK)、施用氮、磷化肥(NP)、施用磷、钾化肥(PK)、施用氮、磷、钾化肥(NPK)、施用氮、磷、钾化肥及有机肥(NPKM)、施用氮、磷、钾化肥及秸秆(NPKS)和施用氮、磷、钾化肥及增量有机肥(NPKM+)处理和旱作系统、稻麦轮作系统、双季稻系统三种轮作方式。主要结果和结论如下:长期施肥条件下土壤磷盈亏速率随时间的变化不大,但不同处理间的差异显著,各处理土壤磷盈亏速率的顺序为CK、N、NK< PK、NP、NPK、NPKS < NPKM、NPKM+。施用NPK肥,土壤磷盈余速率为26 kg/hm2/yr～149 kg/hm2/yr。土壤磷盈余速率与磷肥施用量呈显著正相关关系(p < 0.01)。施用磷肥处理(NP、PK、NPK、NPKM、NPKM+、NPKS)的土壤全磷含量高于不施磷肥处理(CK、N、NK)。不施肥处理(CK)的土壤全磷在乌鲁木齐、南昌和望城呈下降趋势;施用NPK化肥后,全磷含量呈持平状态,平均值分别为0.81 g/kg、0.70 g/kg、0.89 g/kg。其它试验点在不施肥处理(CK)下,全磷的多年变化不大,平均值为0.45 g/kg～1.11g/kg;施用NPK化肥后,平均值为0.58 g/kg～1.33 g/kg。说明长期施用磷肥对保持和提高土壤全磷的含量具有重要作用。施用磷肥显著提高了土壤的有效磷含量,而有效磷含量提高的幅度与土壤磷的主要形态有关。施用NPK化肥,盈余速率每提高100 kg/hm2/yr,以有机磷(Po)为主要形态的哈尔滨平均每年所能提高的土壤有效磷量为8.77 mg/kg,以闭蓄态磷(O-P)为主要形态的祁阳为4.03 mg/kg,大于以钙磷(Ca-P)为主要形态的地区(1.38 mg/kg～2.96 mg/kg)。说明在以有机磷和闭蓄态磷为主要土壤磷形态的土壤上施用磷肥较以钙磷为主要形态的土壤更能有效的提高土壤有效磷含量。有效磷的增加促进了农田作物吸磷量的提高。土壤有效磷与吸磷量关系符合直角双曲线模型( ),即当土壤有效磷含量达到一定阈值的时候,有效磷的增加已经无法带来作物吸磷量的增长。不同地区的作物最大吸磷量有显著差别,一年一熟的公主岭地区作物最大吸磷量为184 kg/hm~2,远高于其它地区;而其它一年一熟的乌鲁木齐和平凉地区作物最大吸磷量为38 kg/hm~2和16 kg/hm~2,低于其它轮作方式,包括一年两熟小麦-玉米轮作区的49 kg/hm~2～60 kg/hm~2,和一年两熟双季稻轮作区的48 kg/hm~2～76 kg/hm~2。说明土壤有效磷含量是作物吸磷量的重要影响因素,而轮作制度的不同则影响了农田作物的最大吸磷量。我国16个典型农田上小麦、玉米、水稻的磷肥回收率、利用率和农学效率的变化在空间上表现为一定的变异特征。施肥量不同时,各试验点农田的作物磷肥效率均符合报酬递减效应,施磷量较高(化肥磷年施用量为135kg/hm2～225 kg/hm2)的昌平、郑州、重庆、遂宁、福州地区的作物(小麦、玉米、水稻)磷肥回收率、利用率、农学效率年平均变化量低于施磷量较低(化肥磷年施用量为60 kg/hm~2～90 kg/hm~2)的哈尔滨、乌鲁木齐、平凉、进贤(旱地)、进贤(水田)、杨凌、祁阳、武昌、南昌地区。施肥量相近时,无机钙磷为主要形态地区的小麦、玉米磷肥回收率、利用率、农学效率变化速率,大于有机磷和无机闭蓄态磷为主要形态的地区。施用NPK条件下,无机钙磷为主要形态地区的小麦磷肥利用率平均每年增长1.0～1.6个百分点,有机磷为主要形态哈尔滨地区增加0.3个百分点;无机闭蓄态磷为主要形态祁阳地区的小麦磷肥利用率持平,平均值为10%。施肥量接近、并且土壤磷主要形态一致的情况下,轮作制度不同,作物的磷肥效率也有差异。施用NPK条件下,一年一熟的乌鲁木齐地区的玉米磷肥利用率平均值为11%,低于一年两熟地区杨凌的43%。以上结果表明,施磷量、土壤磷的主要形态和农田轮作制度从不同层次上影响了作物的磷肥效率。长期施用磷肥提高了土壤全磷、有效磷含量和磷盈亏速率,有效磷的变化速率与土壤磷的主要形态有关。作物吸磷量与土壤有效磷含量的关系符合直角双曲线模型,一年一熟地区的作物最大吸磷量低于一年两熟地区。施磷量、土壤磷的主要形态和农田轮作制度是作物磷肥效率变化的重要影响因素。本论文的研究为合理施用磷肥和提高磷肥效率提供了理论依据。更多还原

【Abstract】 Phosphorus is the essential element for plant growth, but easily fixed in the soil. Hence, phosphorus use efficiency was an important issue for sustainable agricultural production in China. Sixteen long-term field experiments were conducted from China to evaluate soil available phosphorus, crop uptake, phosphorus balance (i.e., application rate minus uptake rate), phosphorus recovery efficiency (PRE), phosphorus use efficiency (PUE), phosphorus agriculture efficiency (PAE), and phosphorus physiology efficiency (PPE). There were nine treatments: non-fertilization (CK), nitrogen fertilization (N), nitrogen-potassium fertilization (NK), nitrogen-phosphorus fertilization (NP), phosphorus-potassium fertilization (PK), nitrogen-phosphorus-potassium fertilization (NPK), manure with NPK fertilization (NPKM), straw return with inorganic fertilizer (NPKS), high rates of manure and NPK fertilization (NPKM+) with upland, rice-wheat, and rice-rice cropping systems. The key findings are given as follows:The phosphorus balance showed little changes over the entire studying period across all the sites. There were significant differences in the averaged phosphorus balance among different treatments, with an order of CK、N、NK< PK、NP、NPK、NPKS < NPKM、NPKM+. For the NPK treatment that was applied to all the sites, the averaged phosphorus balance (26 kg/hm~2/yr -149 kg/hm~2/yr) showed a significantly positive relationship (p < 0.01) with phosphorus application rate.Soil total P contents with phosphorus treatments (NP, PK, NPK, NPKM, NPKM+, and NPKS) were higher than those of non-phosphorus treatments (CK, N, and NK). Total P decreased under the CK treatment, but maintained the same levels under the NPK treatment at the Urumqi, Nanchang, and Wangcheng sites. For the NPK treatment, averaged total P was 0.81 g/kg, 0.70 g/kg, and 0.89 g/kg at the three sites, respectively. Total P was unchanged under the CK (0.45 g/kg - 1.11g/kg) and NPK (0.58 g/kg - 1.33 g/kg) treatments at the other sites. The results indicated that phosphorus fertilizer was the important factor to improve soil total P.Soil available P contents increased when the rate of soil phosphorus surplus increased. The change rate of soil available P contents is related with the main fractions of soil phosphorus at the sixteen sites. The soil available P contents change rates at sites where main fraction of soil phosphorus of organic-P (Harbin, 8.77 mg/kg) and occluded-P (Qiyang, 4.03 mg/kg) were higher than those with the main fraction of Ca-P(1.38 mg/kg-2.96 mg/kg).Crop phosphorus uptake increased when the soil available P improved. The relationship between soil available P and phosphorus uptake by crop can be modeled by rectangular hyperbolic model ( ). Crop phosphorus uptake never increased when soil available P attained threshold. The threshold in the rectangular hyperbolic model was parameter“a”, called the maximum phosphorus uptake rate (P uptake max). The P uptake max was difference among different regions. The P uptake max at Gongzhuling with single cropping system was 184 kg/hm~2, apparantly higher than the other regions. However, the other single cropping system, such as at Urumqi and Pingliang, the P uptake max were 38 kg/hm~2 and 16 kg/hm~2, lower than that of the double cropping systems (wheat-maize and rice-rice double cropping system).Characteristics of crop (wheat, maize, and rice) phosphorus use efficiency accorded with reward descending rule. Crop PRE, PUE, and PAE at sites with high rate of phosphorus application (chemical phosphorus application rate was 135kg/hm~2-225 kg/hm~2) including Changping, Zhengzhou, Chongqing, Suining, and Fuzhou sites were higher than those with the low rate of phosphorus application (chemical phosphorus application rate was 60 kg/hm~2-90 kg/hm~2) included Harbin, Urumqi, Pingliang, Jinxian (upland), Jinxian (paddy), Yangling, Qiyang, Wuchang, and Nanchang sites. The rates of PRE, PUE, and PAE on Ca-P rich soils were higher than that of the main fraction of soil phosphorus of organic-P and occluded-P sites when the phosphorus application rate was similar. In the NPK treatment, wheat PUE increased 1.0-1.6 point per year at sites where main phosphorus form was Ca-P. Whereas the value was 0.3 point at Harbin whose main phosphorus form was organic-P, wheat PUE unchanged at Qiyang whose main phosphorus form was occluded-P, averaged PUE was 10%. Furthermore, crop PRE, PUE, and PAE were difference among different cropping systems. In the NPK treatment, averaged maize PUE was 11% at Urumqi site with single cropping system lower than 43% at Yangling site of double cropping system. The results showed that phosphorus efficency were influced by application rate, soil phosphorus formation, and cropping system.Soil total P, available P, and phosphorus balance rate increased under long term phosphorus fertilization. The change rate of soil available phosphorus contents is related with the main fractions of soil phosphorus. The relationship between soil available phosphorus and phosphorus uptake can be modeled by rectangular hyperbolic model. The P uptake max in single cropping system was lower than that in the double cropping systems. Phosphorus application rate, soil phosphorus formation, and cropping system were important influnce factors of phosphorus efficency. The results provided academic basis of fertilization at various regions.更多还原