ABSTRACT

Relating phosphorus (P) fertilization to crop demand in sugarcane (Saccharum spp.) grown on mineral soils in southern Florida is critical for minimized environmental impact and sustained crop production. Previous P fertilizer recommendations date to 1974 and so revised recommendations are needed for sugarcane on these soils which account for 29% of the crop in Florida. Phosphorus rate studies were conducted at seven field locations (16 total site-crop years) with P rates of 0 to 73 kg P ha⁻¹ at Site 1 and 0 to 61 kg P ha⁻¹ at Sites 2–7 using small-plots (82 or 120 m² plots) on four soil series representing Spodosols, Entisols, and Alfisols. Soil P extractions with Mehlich 3, 0.7 M ammonium acetate, and water were evaluated in relation to relative sucrose yield and leaf P concentrations. Mehlich 3 had stronger relationships with relative yield and leaf P and a Mehlich 3 P value of 80 g m⁻³ is proposed as a critical value above which no P fertilizer would be required. Without added P fertilizer, Mehlich 3-extractable P values decreased annually by an average of 20%. Results suggest maintaining 36.7 kg P ha⁻¹ as the maximum P fertilizer rate for sugarcane in mineral soils.

Abbreviations: EAA: Everglades Agricultural Area; BMPs: best management practices; DAP: diammonium phosphate; MCH: megagram (Mg) cane ha⁻¹; MSH: megagram (Mg) sucrose ha⁻¹; KSM: kg sucrose Mg⁻¹ cane; M3P: Mehlich 3-extractable soil P; AmAcP: ammonium acetate-extractable soil P; Pw: water-extractable soil P

摘要

将磷 (P) 施肥与生长在佛罗里达州南部矿质土壤上的甘蔗 ( Saccharum spp.) 的作物需求联系起来，对于最大限度地减少对环境的影响和持续的作物生产至关重要。以前的磷肥建议可以追溯到 1974 年，因此需要对这些土壤上的甘蔗进行修订建议，这些土壤占佛罗里达州作物的 29%。磷率研究在七个田间地点（总共 16 个田间作物年）进行，地点 1 的磷率为 0 至 73 kg P ha ^-1 ，地点 2-7 的磷率为0 至 61 kg P ha ^-1，使用小块（82 或 120 m ²图）在代表 Spodosols、Entisols 和 Alfisols 的四个土壤系列上。用 Mehlich 3、0.7 M 醋酸铵和水提取土壤磷与相对蔗糖产量和叶片磷浓度的关系进行了评估。Mehlich 3 与相对产量和叶片P 具有更强的关系，并且建议将80 gm ^-3的Mehlich 3 P 值作为临界值，在该临界值之上将不需要磷肥。在不添加磷肥的情况下，Mehlich 3-extractable P 值每年平均下降 20%。结果表明维持 36.7 kg P ha ^-1作为矿质土壤中甘蔗的最大磷肥用量。

缩写：EAA：大沼泽地农业区；BMP：最佳管理实践；DAP：磷酸二铵；MCH：兆克（Mg）甘蔗 ha ^-1；MSH：兆克 (Mg) 蔗糖 ha ^-1；KSM：kg蔗糖Mg ^-1甘蔗；M3P：Mehlich 3-可萃取土壤 P；AmAcP：醋酸铵可萃取土壤P；Pw：可抽水的土壤P