基于甘蔗产量与土壤磷素平衡的磷肥施用量研究

Research on Phosphorus Application Rate Based on Sugarcane Yield and Phosphorus Balance in Soil

【目的】探讨南方赤红壤蔗区基于甘蔗产量与土壤磷素平衡的磷肥施用量,为该地区农田磷素高效利用与科学施磷提供参考依据。【方法】于2014-2016年在广西甘蔗主产区(南宁市武鸣区)布置田间定位试验,共设5个磷肥施用量水平,分别是0(P0)、75 kg P_(2)O_(5)·hm^(-2)(P1)、150 kg P_(2)O_(5)·hm^(-2)(P2)、300 kg P_(2)O_(5)·hm^(-2)(P3)和600 kg P_(2)O_(5)·hm^(-2)(P4),连续3年测定甘蔗蔗茎、蔗叶产量和土壤Olsen-P含量,采用Mitscherlich模型拟合蔗茎产量对Olsen-P的响应曲线,计算土壤Olsen-P农学阈值,并分析植株磷含量,计算甘蔗吸磷量,磷肥利用率和磷素表观平衡状况。【结果】与P1处理相比,P2处理蔗茎产量显著提高8.3%(2014年)、18.0%(2015年)和15.5%(2016年)。蔗叶和地上部产量均以P2或P3处理最高,但不同施磷量间蔗茎、蔗叶和地上部产量整体无显著差异。P2-P4处理蔗茎磷累积量、蔗叶磷累积量和地上部磷累积量也相当。土壤Olsen-P含量、磷素表观平衡量和磷素盈余率均随施磷量的增加而显著增加,而磷素表观回收率和磷素偏生产力随施磷量的增加逐渐下降,以P1处理最高,显著高于P3和P4处理。Mitscherlich方程拟合获得Olsen-P农学阈值为13.4 mg·kg^(-1)。相关分析表明,施磷量与磷素盈余率、磷素盈余率与土壤Olsen-P含量呈极显著的线性正相关关系(P<0.01);磷素盈余率与甘蔗蔗茎产量呈极显著二次相关(P<0.01),与磷素表观回收利用率、磷素偏生产力呈极显著指数相关(P<0.01)。当施磷量为40.9 kg·hm^(-2)时,磷素盈余率为0,土壤Olsen-P含量为15.87 mg·kg^(-1),甘蔗蔗茎产量为94.2 t·hm^(-2)。线性加平台拟合下的优化施磷量,土壤磷素盈余率为216.2%-232.7%,土壤Olsen-P含量为24.7-25.4 mg·kg^(-1),甘蔗蔗茎产量为99.7-100 t·hm^(-2)。【结论】在Olsen-P含量较高的蔗区,40.9 kgP_(2)O_(5)·hm^(-2)施用量能维持土壤磷素平衡,保持土壤适宜的Olsen-P含量,获得较高的产量与磷肥利用率,可以作为推荐的适宜施磷量。

【Objective】This study was conducted to explore the phosphate fertilizer rate based on sugarcane yield and phosphorus(P)balance in soil,with an aim to provide a reference for the efficient utilization and scientific management of P in farmland.【Method】A 3-year continuous field trail was conducted in Wuming district of Nanning city of Guangxi province from 2014 to 2016,which was designed with five phosphate fertilization treatments,including non-phosphate fertilization(P0),75 kg P_(2)O_(5)·hm^(-2)(P1),150 kg P_(2)O_(5)·hm^(-2)(P2),300 kg P_(2)O_(5)·hm^(-2)(P3)and 600 kg P_(2)O_(5)·hm^(-2)(P4).The yield of cane and leaves and Olsen-P content in soil were measured,and the relation between cane yield and Olsen-P was evaluated by Mitscherlich model.The agronomic threshold of soil Olsen-P was also calculated.Plant P content,P uptake,P utilization efficiency and P balance in soil were further analyzed.【Result】Compared with P0 treatment,the cane yield was significantly increased by 8.3%(2014),18.0%(2015)and 15.5%(2016)under P2 treatment.P2 or P3 treatments had the highest yields for leaves and above-ground part,but there was no significant difference in cane,leaves and above-ground part among different P application rates.P accumulations in cane,leaves and above were also similar among P2 to P4 treatments.Olsen-P content,P balance and P surplus rate increased significantly with the increase of P application rate,while the PRE and PPFP decreased gradually with the increase of P application rate;where P1 treatment was the highest,which was significantly higher than that under P3 and P4 treatments.The agronomic threshold of Olsne-P was 13.4 mg kg-1 based on Mitscherlich model.Correlation analysis showed that P surplus rate was significantly positively correlated with P application rate and soil Olsen-P(P<0.01),and which was significantly quadratic correlated with sugarcane stem yield(P<0.01),and significantly exponential correlated with PRE and PPFP(P<0.01).When P application rate was 40.9 kg·hm^(-2),P surplus rate,soil Olsen-P content and cane yield were 0,15.87 mg kg-1 and 94.2 t·hm^(-2),respectively.While the maximum cane yield was obtained by linear and platform fitting,soil P surplus rate,Olsen-P content and cane yield were 216.2%-232.7%,24.7-25.4 mg·kg-1 and 99.7-100 t·hm^(-2),respectively.【Conclusion】In lateritic red soil with relatively high Olsen-P content,the P application rate of 40.9 kg·hm^(-2)would maintain the soil Olsen P content,meet the demand for high yield and high phosphorus utilization efficiency.Thus,it could be used as the recommended P application amount.