Growth and phosphorus uptake of maize cultivated alone,in mixed culture with other crops or after incorporation of their residues

Intercropping or rotating of P‐efficient crop species which mobilize sparingly soluble P by their root exudates can have beneficial effects on growth and P uptake of P‐inefficient species. We aimed at studying the effect of intercropping or incorporating of crop residues of P‐efficient crops on the components of maize P‐uptake, i.e. the root‐system size and P influx (P‐uptake rate per unit root length). This was studied in 3 pot experiments in a low‐P sandy soil. In the first experiment, maize was intercropped with white lupine, sugar beet or oilseed rape, and with groundnut in the second experiment. In the third experiment, maize was grown after incorporating the crop residues of white lupine, sugar beet or oilseed rape. Maize growth and yield was strongly inhibited when intercropped with white lupine, sugar beet or oilseed rape, probably because of competition for nutrients. But with groundnut as the accompanying species, maize yield was increased by a factor of 3, mainly because of an enhanced P influx. Crop residues of oilseed rape and sugar beet increased the yield of maize by factors 2 and 1.6, respectively, because of a 3 and 2 times higher P uptake as compared to maize grown after maize without incorporation of crop residue. The reason for the higher maize P‐uptake after oilseed rape was an 11 times higher P influx as compared to maize without crop residues, and after sugar beet residues because of an enhanced root growth and a 4 times higher P influx. Lupine residues did not improve maize growth, mainly because of a low P influx, which was even less than that of maize grown without crop residues. The soil solution P concentration and calcium acetate lactate‐extractable P (CAL P) measured in this study did not reflect the P availability as indicated by the plants (P uptake, P influx). This indicates that other mechanisms such as P mobilization in the rhizosphere by root exudates or cell‐wall components were responsible for the increased P availability. These mechanisms need further investigation.     

植物篱种植模式及其在我国的研究和应用

植物篱种植模式作为一种坡地保护性耕作和持续利用技术,自20世纪70年代以来在热带地区研究和应用较为广泛,本文概述了我国近10余年来的研究和应用进展。这一模式在20世纪80年代中期进行了短暂的试验,20世纪90年代以来在金沙江干旱河谷地区和三峡地区结合当地实际需求和植物篱种植模式的特点,对植物篱种植模式进行了研究,使之适合我国山区和坡耕地的应用;对植物篱的生态效益、社会效益和经济效益均进行了较深入细致的试验、研究,并进行较大面积的示范和推广应用,同时引起了国内很多研究机构和应用部门的关注,尽管在1997年以后其它区域也随之进行了一些类似的试验和研究,但国内目前只有金沙江干旱河谷地区和三峡地区在研究和应用方面较系统和深入。最后还对国内在植物篱认识上的一些问题,以及需要进一步深入开展的工作进行了讨论。     

紫色土丘陵林农间种模式种间适应及作物种类选择试验

1997~1998年在试验区进行了林农间适应及作物种类选择试验,结果如下;适度的林木郁闭对作物生长有利,郁闭度为0.35时,其生物产量和经济产量均优于0.125;郁闭度为0.67以上,不宜进行间种。适宜于试区土地条件的冬春作物有满园花、油菜;夏季作物有西瓜、甘薯、凉茹、辣椒、大豆、花生、豌豆等,但从防侵蚀角度考虑,甘薯、凉茹等收获地下块根的作物不宜选用。     

林草间作地土壤低吸力段持水性能的初步研究

以庄浪县5种林草间作模式为对象,在田间采用张力计法测定各模式地的低吸力段土壤水分特征曲线,分析各模式地的土壤持水性能,比较不同模式地的比水容量,结果表明,各模式地土壤含水率随吸力变化较快;五种模式不同土层土壤持水力存在明显差异,表层土壤持水力较大,60cm土层土壤持水能力最差。仁用杏+红豆草模式地土壤持水能力和供水能力最强,是最为耐旱模式,油松+紫花苜蓿模式供水能力最差。     

小麦收获期对麦套棉田捕食性天敌和棉花苗蚜的影响

2004-2005年在冀南棉区研究了小麦收获期对麦套棉田中捕食性天敌和棉花苗蚜的影响。小麦收获期共设3个水平,分别是6月5日、6月10日和6月15日收获小麦。结果表明:2004年3个时期收获小麦对棉田的益害比(天敌和棉蚜的比值)无显著影响(t>0.05);2005年6月5日收获小麦,显著增加了棉田的益害比(t<0.05),6月10日和6月15日收获小麦对棉田的益害比无显著影响(t>0.05)。说明在麦套棉田中,麦田天敌到棉田的有效转移受麦蚜-天敌-棉蚜三者发生高峰期的影响,不同年份天敌的转移情况有所不同。麦蚜发生高峰期早则小麦天敌向棉田转移早,并能有效控制苗期蚜虫的危害,在麦熟期收获小麦,对棉田天敌的数量影响不大;反之,若麦蚜发生高峰期晚,麦田天敌发生期也会相应延后,在麦熟期收获小麦则会引起棉田天敌的增加。因此,棉田天敌数量变化受小麦收获期的影响,但与麦蚜和麦田天敌的发生动态有直接关系。     

灌溉与施磷对小麦-玉米-马铃薯间套群体作物生理特征的影响

在景泰大田中进行了三个灌水水平,三个施磷量的试验。为了探讨水磷对复合群体作物生理特征的调控及其产量效应,结果表明:灌溉和供磷对间套群体中作物的生理特征具有明显的调控效应。在充分的磷肥供应和适当的水分灌溉条件下,作物叶绿素含量高,叶片水分状态良好,根系生长旺盛,根冠比例协调,能够获得较高的经济产量。同时,在所有的处理中,中灌(1 050m3 /hm2)和高磷(纯 P2O5150 kg/hm2)处理的经济产量最高。单作小麦、间作小麦、间作玉米、间作马铃薯在该处理条件下的产量依次是 7 253.8kg/hm2、3 320.5kg/hm2、6 269.3 kg/hm2、13 801.9 kg/hm2。     

苹果梨果园土壤营养与叶片营养的调查

对内蒙古河套地区15个苹果梨果园进行土壤与叶片营养调查。结果表明,土壤营养普遍贫瘠,N、P、有机质含量偏低,K含量中等;树体N、Fe含量偏高,P、Ca、Mg、Mn、Cu含量适中,K、Zn含量偏低;土壤与叶片营养主要影响果实的硬度和酸度;提高土壤营养可提高树体营养水平,进而提高果实品质。     

Establishment of trees on mixtures of pulverized fuel ash and Gypsum. Part II: Nutrition and trace elements

Nutrients and trace elements were determined in the foliage of nine tree species grown in mixtures of pulverized fuel ash (PFA) and gypsum. No serious macronutrient deficiencies were observed. Treatments with PFA consistently increased foliar levels of boron, potassium and molybdenum, and the poor performance of some tree species in pure PFA was attributed to boron toxicity. Gypsum hindered the uptake of boron when mixed with PFA, however, and co-disposal of the two wastes could be used to minimize problems associated with boron toxicity.     

冀西北高原还林地林带间水分动态与资源适度利用研究

针对冀西北坝上还林地间作的4种模式,对林带间水分进行监测研究。结果表明:4龄榆树与林带间荒草地耗水量差异不显著;林带间作大豆、苜蓿、小南瓜使得远林带点耗水量分别高于林带间荒草地5.2、11.6、20.0 mm,近林带点差异不显著;间种作物未影响幼林的生长,且能获得较好的经济产值;还林地间作小南瓜,不仅可通过瓜蔓郁蔽效应改善林带土壤水分,而且可获得当地主栽作物1.85倍的经济产值,是一生态-经济效益兼顾的幼林地资源适度利用范式。     

阴山北麓农牧交错区麦薯带状间作农田土壤抗风蚀能力研究

对麦薯带状间作农田土壤的抗风蚀能力进行了探讨.结果表明,该措施能够减少水分蒸发,增加地表土壤含水率0.22%~2.6%,增大地表空气动力学粗糙度0.03~3.81 cm,降低近地表风速6%~46%,减少土壤风蚀0.5%~84%.在定量研究的基础上,提出了翻耕带有效抗风蚀宽度为5 m.