Abstract:

【Objective】 The aims of this paper were to determine the reason for high input but low utilization of phosphorus (P) fertilizer, and to provide a basis for raising the utilization rate of P and reducing environmental pollution under greenhouse cultivation. 【Method】 To investigate the management of representative greenhouse cultivation in Shenyang, Liaoning Province, samples of soil from greenhouses of different planting years and also an open field within the researched area were collected and analyzed for the accumulation of inorganic P fractions. 【Result】 In greenhouse soil, the contents of total P, inorganic P and available P all increased, with their maximum values in the topsoil (0-20 cm), and average values of 3.1, 3.3 and 3.6 times that of the open field soil, respectively. The content of inorganic P accounted for 92.1% of total P, while available P only accounted for 16.6%. In greenhouse soil, the average contents of Ca8-P, Al-P, Ca2-P, Fe-P, O-P and Ca10-P were 10.2, 5.9, 5.0, 3.1, 2.7 and 1.5 times that of the open field soils, respectively, and the contents of each component of total P were Al-P (26.1%) > Fe-P (18.1%) > O-P (17.6%) > Ca10-P (14.4%) > Ca8-P (10.5%) > Ca2-P (5.6%). The nutrient availability of Ca2-P was high but its accumulation was low, while the availabilities of O-P and Ca10-P were high but their accumulations were low, which seriously decreased the utilization rate of P. In greenhouse soil, 49.3% of total inorganic P in topsoil (0–20 cm) was Al-P and Fe-P, while 46.6–78.2% of total inorganic P in deep soil was O-P and Ca10-P, which both increased with depth of soil. 【Conclusion】 Under greenhouse cultivation, the content of P increased greatly, with more than half of the total being Ca10-P, O-P and Fe-P. Improving the bioavailability of these components of inorganic P with low nutrient availability is the key to establish an environment-friendly nutrient management system compatible with greenhouse conditions.

Key words: greenhouse soil, inorganic phosphorus fractions, accumulation, migration