高磷土壤减量施磷对果蔗磷肥利用效率和土壤酶活性的影响

生产中为了追求高收益,果蔗种植中磷肥过量投入现象普遍,造成肥料效率降低和土壤肥力失衡等问题。本研究在广东湛江高磷红壤区采取田间定位试验（初始有效磷含量为234.80mg/kg）,研究磷肥减量100%（P0）、50%（P1）、20%（P2）和当地常规施磷（CK,600kg P₂O₅/hm²）处理下,果蔗磷肥利用效率以及土壤酶活性的变化特征。结果表明,经过连续2年试验后,果蔗产量、糖分含量、株高和茎径等品质性状均表现为P2＞CK＞P1＞P0。P2处理磷肥利用率最高（32.09%）,P1处理最低（28.08%）;农学效率为P2＞P1＞CK;磷肥偏生产力为P1＞P2＞CK。随着施磷水平的降低,α-葡萄糖苷酶和与氧化还原相关的过氧化物酶、多酚氧化酶等酶的活性提高,β-葡萄糖苷酶、纤维二糖苷酶、乙酰氨基葡萄糖苷酶以及磷酸酶等水解酶活性均呈现下降趋势;与氮转化相关的亮氨酸氨肽酶和脲酶活性均以P2处理最低,P0处理最高。此外,土壤酶活性与土壤养分含量显著相关（P＜0.05）。综合果蔗产量、品质、磷肥利用效率以及土壤酶活性及其对生长影响,较常规施磷减量20%（P2）是该地区果蔗的适宜用量。

Effects of Reducing Phosphorus Application in High-P Soils on the P Efficiency of Chewing Cane and Soil Enzyme Activity

In pursuit of high economic benefits, the excessive input of P fertilizer is common in the cultivation of chewing cane resulting in some problems such as the imbalance of soil fertility and reduction of fertilizer efficiency. In the high phosphorus (P) red soil area of Zhanjiang, Guangdong province, the initial soil available P was as high as 234.80mg/kg. Field positioning experiments were carried out to study the characteristics of chewing cane P utilization, and soil enzyme activities after continuous different P reduction measures reducing P of 100% (P0), 50% (P1), 20% (P2), and local customary P application (CK, 600kg P₂O₅/ha). The results showed that under different P application levels for two consecutive years, the yield, as well as quality traits of sugar content, plant height, and stem diameter of chewing cane were P2 > CK > P1 > P0. Among all P applied treatments, the P use efficiency was the highest in P2, with a value of 32.09%, and the lowest in P1 treatment, with a value of 28.08%. The agronomic efficiency was P2 > P1 > CK. The partial productivity of P was P1 > P2 > CK. As the decrease of P application level, the activities of α-glucosidase and redox-related enzymes, peroxidase and polyphenol oxidase increased; the activities of hydrolases such as enzymes associated with carbon conversion, β-glucosidase, cellobiohydrolase and N-acetylglucosaminidase and phosphatases, decreased; and the activities of leucine aminopeptidase and urease were the highest in P0 treatment and the lowest in P2 treatment. Besides, soil enzyme activity was closely related to soil nutrients, and the correlation was significant (P < 0.05). In combination with the yield, quality of chewing cane, P use efficiency, the soil enzyme activity, and the effects on cane reduction of P fertilizer by 20% could be the recommended amount of P for chewing cane in this region.