Nitrogen–Potassium Concentrated Complex Fertilizers versus Nitrogen–Potassium Blends: Effects on Potassium Uptake by Perennial Ryegrass

Abstract

It was hypothesized that supplying potassium (K) in concentrated complex fertilizer (CCF) form with nitrogen (N) (NK CCF) to all fertilizer microsites, rather than in NK‐blended fertilizer form to a fraction of the total fertilizer microsites, should enhance the rate of K uptake by perennial ryegrass. Two complementary pot experiments were conducted to test this hypothesis. The results demonstrated that plants fertilized with an NK CCF absorbed K at faster rates than those fertilized with an NK blend and that use of K₂SO₄ in place of KCl as the K source lowered the rate of K uptake by plants regardless of fertilizer form. Form of fertilizer (i.e., CCF or blend), however, had no effect on NH₄ ⁺ or NO₃ ^? uptake. Unfortunately, the positive effects of the CCF on K absorption were only manifest during the second 2 weeks of regrowth and did not result in significant improvements in dry matter production by the end of the 5‐week regrowth periods.     

Is crop N demand more closely related to dry matter accumulation or leaf area expansion during vegetative growth?

The critical crop nitrogen uptake is defined as the minimum nitrogen uptake necessary to achieve maximum biomass accumulation (W). Across a range of crops, the critical N uptake is related to W by a power function with a coefficient less than unity that suggests crop N uptake is co-regulated by both soil N supply and biomass accumulation. However, crop N demand is also often linearly related to the expansion of the leaf area index (LAI) during the vegetative growth period. This suggests that crop N demand could be also linked with LAI extension. In this paper, we develop theory to combine these two concepts within a common framework. The aim of this paper is to determine whether generic relationships between N uptake, biomass accumulation, and LAI expansion could be identified that would be robust across both species and environment types. To that end, we used the framework to analyze data on a range of species, including C₃ and C₄ ones and mono- and di-cotyledonous crops. All crops were grown in either temperate or tropical and subtropical environments without limitations on N supply. The relationship between N uptake and biomass was more robust, across environment types, than the relationship of LAI with biomass. In general, C₃ species had a higher N uptake per unit biomass than C₄ species, whereas dicotyledonous species tended to have higher LAI per unit biomass than monocotyledonous ones. Species differences in N uptake per unit biomass were partly associated with differences in LAI and N-partitioning. Consequently the critical leaf-N uptake per unit LAI (specific leaf nitrogen, SLN) was relatively constant across species at 1.8–2.0 g m⁻², a value that was close to published data on the critical SLN of new leaves at the top of the canopy. Our results indicate that critical N uptake curves as a function of biomass accumulation may provide a robust platform for simulating N uptake of a species. However, if crop simulation models are to capture the genotypic and environmental control of crop N dynamics in a physiologically functional manner, plant growth has to be considered as the sum of a metabolic (e.g. leaves) and a structural (e.g. stems) compartment, each with its own demand for metabolic and structural N.     

Determination of molybdenum in plant tissue by graphite furnace atomic absorption spectrophotometry (GFAAS)

Abstract

The analysis of molybdenum in plant tissue using graphite furnace atomic absorption spectrophotometry (GFAAS) is described. The method involved wet digestion using a mixture of sulphuric, nitric and perchloric acids followed by a solvent extraction procedure. Molybdenum was extracted into di‐iso butyl ketone (DIBK) as the iron‐thiocyanate complex. The extract was then analysed for molybdenum by GFAAS.

The results of analyses of the reference plant materials (orchard leaves and citrus leaves) of the National Bureau of Standards (NBS) compared very well with the certified values. Other types of plant tissue were also analysed and the results correlated well with those obtained by an alternative method.     

石墨炉原子吸收标准加入校正法测定土壤中痕量镉

选用硝酸-氢氟酸-高氯酸、硝酸-盐酸-氢氟酸-高氯酸2种消解体系,建立了石墨炉原子吸收标准加入校正法测定土壤中镉的方法,能够实现对土壤镉的准确测定.以硝酸钯为基体改进剂,优化灰化温度为550℃,原子化温度为1600℃.分别取土壤标准样品GBW07452、GBW07388经微波消解或全自动消解后,定量加入到标准溶液系列中...     

微波消解-火焰原子吸收光谱法测定芋艿中矿质元素

为研究不同品种芋艿中金属元素和微量元素的含量,采用微波消解-火焰原子吸收光谱法测定不同品种芋艿中4种矿质元素含量。结果表明:不同品种芋艿中均含有丰富的Fe、Zn、Cu和Mn 4种矿质元素,且微量元素含量均表现为FeZnCuMn;其中Fe含量最高,为13.969 3~17.340 8mg·kg-1;Zn含量次之,为4.966 5~5.631 9 mg·kg-1。标准曲线相关系数为0.998 2~0.999 9,加标回收率为98.666 7%~101.646 7%,标准偏差(RSD)小于2%。     

日粮蛋白质水平对生长期闽南黄牛氮代谢的影响

选用9头14月龄闽南黄牛公牛,按重复3×3拉丁方设计,进行了氮平衡试验。研究了日粮蛋白质水平对氮消化与沉积规律及血液某些相关指标的影响。结果表明:随着蛋白质水平的提高,氮的进食量显著增加;氮的表观消化率、氮沉积量也显著增加(P<0.01)。氮的表观消化率(％)=43.26+0.58X,(r=0.9412,n=9);沉积氮(g/d)=1.86+0.37X,(r=0.9216,n=9)。     

Geostatistical Analysis of Yield,Soil Properties and Crop Management Practices in Paddy Rice Fields

Abstract

We examined the possible benefit of rational site-specific crop management practices in 17 paddy fields located in an area of 2.0 ha for the prevalence of precision agriculture methods on a cooperatively managed large-scale farm in Sakurai, Nara Japan. Data on grain yield, soil physicochemical properties and farmer's crop management practices were collected in each paddy field. Unhulled rice yield was estimated at a resolution of 5m ? 5m in an area of 1.2 ha using a yield-monitoring combine. The spatial distribution of the variations for the collected data was characterized using geostatistical procedures. The kriged map of the unhulled rice yield drawn from the results of geostatistical analysis indicated the potential value of rational site-specific crop management using the yield-monitoring combine. The ratio of spatially structured variation to the total variation of brown rice yield, that is, the controllable proportion to total variation, was 75.4%. Each yield component i.e., the number of spikelets per square meter, filled-spikelet percentage and 1000-grain weight contributed 33.7%, 54.7% and 11.6%, respectively, to brown rice yield. These three yield components combined contributed to 96.5% of the brown rice yield variation. The agronomic factors (soil fertility factor, early growth factor, N dressing and uptake factor) contributed 79.7%, 52.1% and 41.8%, respectively, to the variation of these three yield components. Therefore these agronomic factors accounted for 58.1% of the total variation of the brown rice yield and 77.1% (i.e. 58.1% out of 75.4%) of the spatially structured variation of the brown rice yield. This controllable proportion may be a criterion for the prevalence of site-specific crop management in large-scale farm management in general, although only one case study was conducted.     

不同园林树种叶片N·P·K养分内吸收作用

[目的]研究8种亚热带常见园林树种叶片N、P、K内吸收率及其季节变化.[方法]分别采用扩散法、钼锑抗比色法和火焰光度计法对采集叶片N、P、K含量进行测定.[结果]各树种成熟叶养分含量都高于新鲜凋落叶,且大部分呈显著性差异,N、P、K的内吸收率（平均值±标准差）分别为（9.11±3.89）％～ （68.42±2.44）％、（9.94±5.31）％～（60.54±13.74）％和（24.66±12.14）％ ～ （77.15±5.21）％.N和K的内吸收率有显著性差异（P＜0.05）,N和P以及P和K之间差异并不显著;N和P的内吸收率春季低于秋季,K的内吸收率春季高于秋季;常绿树种和落叶树种的养分内吸收率无显著差异;固氮树种（羊蹄甲和黄槐）与非固氮树种的N内吸收率也未出现显著差异.[结论]植物叶片在凋落前发生内吸收作用是一种比较普遍的现象,季节变化只是影响植物叶片养分内吸收的主要因素之一,不同的生活型并没有显著影响植物的内吸收率,固氮作用对植物在N养分供给上作用并不明显.     

原子吸收法测定苦瓜中铁、铜、锌的含量

研究采用火焰原子吸收—分光光度计法同时测定苦瓜中铁、铜、锌含量的方法。进行样品预处理方法筛选和酸度条件试验,结果表明:干法灰化较湿法简便,被测元素无损失;酸介质及其加入量对被测元素稍有影响;检测方法精确度高、操作简便、实用性强,为进一步开发科学的测定方法提供了依据。