冬小麦-夏玉米体系磷效率对鴥土磷素肥力的响应

【目的】研究鴥土区冬小麦-夏玉米轮作体系磷肥利用效率(PUE)和土壤肥力(磷素)的关系,可以界定土壤磷素的最佳管理范围及合理施磷量,为实现作物高产和减少磷素损失提供理论依据。【方法】采取鴥土长期定位试验5个不同磷素水平的土壤,有效磷含量依次为3.90 (F1)、15.00 (F2)、23.60 (F3)、35.70 (F4)和50.00(F5) mg/kg进行盆栽试验,供试作物为小麦‘小偃22’和玉米‘郑单958’。每个磷素水平土壤上设置5个施磷量(P2O5 0、30、60、90、120 kg/hm^2)。作物成熟后,收获地上部所有植株,晒干、脱粒后测定地上部生物量、籽粒产量,籽粒和秸秆样品粉碎后测定其含磷量。作物收获后均匀采集盆内土样约50 g/盆,风干并混匀后分别过1 mm和0.15 mm筛,测定土壤速效磷和全磷含量。计算冬小麦-夏玉米种植体系磷肥利用效率与土壤磷素水平的关系。【结果】F1土壤增施磷肥可显著提高小麦和玉米的籽粒产量,与P0相比,所有施磷处理小麦增产52.2%～119.7%、玉米增产94.7%～212.7%;F2、F3、F4和F5土壤磷肥增产效果不显著。经过两季作物种植,与P0相比,F2土壤施磷60 kg/hm^2、120 kg/hm^2和F5土壤施磷120 kg/hm^2显著提高了全磷含量,其他磷水平土壤全磷含量无显著变化;F1、F2、F3、F4和F5土壤施磷处理的土壤速效磷含量分别增加了-4.08%～434.69%、26.49%～112.77%、6.74%～48.24%、4.07%～43.65%和-4.84%～28.29%。冬小麦磷肥利用效率(PUE)与土壤Olsen-P之间呈显著的正相关关系(P <0.05),P30、P60、P90和P120线性关系决定系数分别达到0.996、0.899、0.760和0.820。夏玉米PUE在P30下随土壤磷素水平的提高呈二次抛物线形式增加,据此可得出在Olsen-P为12.32 mg/kg时PUE达到100%,当土壤速效磷为33.63 mg/kg时PUE达到最大值155.24%;在P60、P90和P120时,PUE随土壤Olsen-P含量上升而直线增加,Olsen-P分别达到12.22 mg/kg、16.64 mg/kg和14.39 mg/kg后维持在一个水平。整个冬小麦-夏玉米体系PUE随土壤速效磷的变化趋势和夏玉米类似,冬小麦(P30)和夏玉米(P30)总施磷量为P2O5 60 kg/hm^2时,可算出土壤速效磷为17.97 mg/kg时PUE达到100%;当速效磷达到40.11 mg/kg时,PUE达到最大值131.51%。在同一磷素水平土壤上,随施磷量增加,小麦和玉米PUE均显著降低,尤其是施磷量高于60 kg/hm^2后。【结论】关中鴥土区冬小麦-夏玉米体系,小麦季土壤速效磷应大致控制在17～40 mg/kg范围内,玉米季土壤速效磷控制在13～34 mg/kg范围内进行管理;整个冬小麦-夏玉米体系将土壤速效磷大概控制在17～40 mg/kg范围内,总推荐施磷量为P2O5 60～120 kg/hm^2为宜。

果蔗磷肥高效施用技术研究

种植果蔗的经济效益较好,为了获得高产,生产上磷肥过量投入现象普遍,造成了土壤磷素大量累积、磷肥利用率较低等问题。建立基于土壤磷素营养状况和磷肥高效利用的果蔗磷肥施用技术具有实践意义。本文收集整理了我国当前果蔗磷肥施用技术的相关研究成果,并结合果蔗磷肥效益田间定位试验数据,总结了果蔗磷肥高效施用的技术方法,包括磷肥用量确定、磷肥施用时间、磷肥品种选择等等,以期降低磷肥投入的同时保证果蔗产量品质。

Effect of Phosphorus Level on the Availability of Some Micronutrients in a Vertic Argiudoll Soil under No-Tillage System in Argentina

There are interactions between phosphorus （P） and some micronutrients which can affect their availability if P is applied as a fertilizer in high concentrations. There are many mechanisms of interactions between P and micronutrients and changes in pH values caused by phosphate fertilization is one of them. These interactions between nutrients might be more pronounced under a no-tillage system which produces stratification and accumulation of few mobile nutrients as P in the surface horizons due to the lack of soil removement. The objectives of this study were： （1） to evaluate the effect of P concentration on the availability ofCu, Zn, Fe and Mn in soil under no-tillage system; （2） to produce maps of nutrients availability and to analyze whether an interaction between nutrients spatial distribution exists. The study was carried out in Parana, province of Entre Rios, in a soil classified as Vertic Argiudol in two consecutive growing seasons （2006 and 2007）. A plot of 1 （one） hectare under no-tillage system with a double-cropped wheat-soybean rotation in sequence （soybean sowing after wheat harvest） was sampled by the grid methods. The results of this study suggest which tillage regime and phosphate fertilization increased P levels in superficial horizons and this produced a negative relationship between micronutrients and P. Regarding the nutrients map distributions, the negative interaction between P and micronutrients was clearly seen in the case ofFe_ Mn and Zn.