地力差减法在黔东南州黄粘泥田水稻测土推荐施肥中的应用研究

通过田间试验,水稻的地力产量、目标产量均与土壤养分测定值正相关;化肥利用率与土壤养分测定值负相关;逐一分析养分平衡法施肥公式中各子项与土壤养分测定值的数量关系．建立推荐施N、P2O5、K2O量分别与土壤速效氮、磷、钾的一一对应函数关系。     

杂交中稻应用配方推荐施肥的增产效果

为了提高农民施肥水平,对杂交中稻进行了习惯施肥与2种推荐施肥的对比试验。结果表明：杂交中稻配方推荐施肥处理较习惯施肥增产1 507.5 kg/hm^2,增收2 412元/hm^2,增产率为22.2%;而增施硅肥可增产135.0 kg/hm^2,增产率为1.6%,增产效果不显著。配方推荐施肥经济效益显著,可大面积推广应用。     

黔东南州油菜测土推荐施肥研究

通过油菜小区试验研究,结果表明:不同施肥量,不同N、P、K配比,均有不同的化肥利用率;土壤养分测定值与目标产量、空白田产量均正相关;土壤养分测定值与化肥利用率负相关;利用测土施肥公式,建立了N、P、K化肥施用量与土壤养分测定值的函数关系,能在产前提出合理的施肥计划。     

中国测土施肥工作的进展和展望

近十多年来，我国在测土施肥方面的研究取得迅速发展，并已大面积推广应用。本文着重对土壤有效养分测定，分析结果的解释，以及施肥量的方法作了综合评述，同时对测土施肥工作存在的问题和今后的发展也进行了讨论。     

华北地区采用无机氮测试和植株速测进行夏玉米氮肥推荐

A field experiment with a split-plot design was carried out at Dongbeiwang Farm in Beijing Municipality to establish reliable N fertilizer recommendation indices for summer maize (Zea mays L.) in northern China using the soil Nmin(mineral N) test as well as the plant nitrate and SPAD (portable chlorophyll meter readings) tests. The results showed that Nrnin sollwert (NS) 60 kg N ha^-1 at the third leaf stage and N rate of 40 to 120 kg N ha^-1 at the tenth leaf stage could meet the N requirement of summer maize with a target yield of 5.5-6 t ha^-1. Sap nitrate concentrations and SPAD chlorophyll meter readings in the latest expanded maize leaves at the tenth leaf stage were positively correlated with NS levels, indicating that plant nitrate and SPAD tests reflected the N nutritional status of maize well. Considering that winter wheat subsequently utilized N after the summer maize harvest, the 0-90 cm soil Nmin (74 kg N ha^-1) and apparent N loss (12 kg N ha^-1) in the NS60＋40 treatment were controlled at environmentally acceptable levels. Therefore NS60＋40, giving a total N supply of 100 kg N ha^-1, was considered the optimal N fertilizer input for summer maize under these experimental conditions.     

OPTIMIZATION OF BIPARTITE JOINS WITH GRAPH THGORY

An optimization approach for multi-relational joins based on the matching concept in graph theory is introduced. The basic idea lies in constructing a join graph from an expression of N-relation query, and seeking for a maximun matching with minimun total weight. The algorithm for bipartition(X, Y) is proposed in this paper.     

玉米病虫草害诊断和咨询专家系统的构建

采用面向对象的方法和VB 6.0程序设计语言,设计和实现了一个玉米病虫草害诊断和咨询专家系统.介绍了该系统的结构和各模块的功能,阐述了系统数据库建立以及主要功能的实现方法,其中数据库的建立以及查询功能的实现是该系统的核心部分.     

充足范围法和修正诊断施肥综合法在荔枝营养诊断中的比较

根据深圳市4个荔枝丰产园制定了糯米糍荔枝叶片N、P、K、Ca、Mg、B、Zn 7个元素的标准值范围及其相应比值参比值等参数，运用充足范围法（标准值法）与修正诊断施肥综合法（M-DRIS）对深圳市2个低产园糯米糍N、P、K、Ca、Mg、B、Zn的丰缺状况进行了诊断．结果表明，与充足范围法相比，M-DRIS不但可以衡量养分相对平衡状况，还能够提供施肥次序和养分潜在缺乏的信息，为荔枝平衡施肥提供参考依据．     

An evaluation of the Olsen test as a measure of plant-available phosphorus in grassland soils derived from basalt parent material

Abstract. Anecdotal and circumstantial evidence have suggested that the Olsen test underestimates plant-available phosphorus (P) in basaltic soils in Northern Ireland. Therefore, the ability of this test to predict plant-available P in basaltic (and non-basaltic) soils was investigated by regressing Olsen-P data against herbage P indices calculated from plant tissue test data using the diagnosis and recommendation integrated system. The average Olsen-P concentration for a range of fields situated on basaltic soils was considerably lower than the average Olsen-P concentration for a range of fields situated on non-basaltic soils, and yet mean sward P status, as given by the herbage P indices, was similar for both groups of fields. Herbage P indices were also much better correlated with Olsen-P measurements in non-basaltic soils than in basaltic soils. Furthermore, at low Olsen-P values (≶9mgPL⁻¹) some swards on basaltic soils were genuinely deficient in P, while others were sufficient or even in surplus for this nutrient. The results confirm that Olsen-P is inadequate as a predictor of plant-available P in basaltic soils. It is concluded that an alternative soil test is needed to provide a reliable assessment of plant-available P in basaltic soils, to prevent overuse of fertilizer and manure P and to minimize the amounts of P entering local watercourses.