Measurement of Fertilizer Leaching from the Root Zone Using an Automated Infiltration Soil Water Sampler in an Unsaturated Sandy Field

In sandy fields with vegetable cultivation, fertilizer leaching may occur and it should be well-controlled. The development of a direct soil water sampler is necessary to examine solute transport and fertilizer leaching in the vadose zone, since soil water reflects timely monitoring of data more accurately than groundwater. We developed a Suction-Controlled Flux Sampler to collect infiltration soil water in a sandy soil. In the present study, we monitored fertilizer leaching in an unsaturated sandy field during the rainy season, while evaluating the sampling performance of SCFS for the sampling of infiltration water. SCFS directly collected the infiltration water effectively over a period of several months in the sandy field and recorded the Water-Collecting Efficiency from 92 to 115% under various infiltration conditions during a period of 50 d. WCE was affected by the rainfall intensity as well as by previous rainfall, which enhanced WCE. The results obtained from the use of SCFS and several sensors demonstrated that the amount of leached water remained low as long as irrigation was applied according to the cultivation manual. However, an unexpected heavy rainfall event led to fertilizer leaching. The fertilizer leaching trend was effectively monitored by several sensors inserted into the soils, while detailed analysis of the components was performed after collection by using SCFS. Direct access to infiltration water enabled to examine the infiltration process and detailed variations in the amounts of discharged anions. The sensor-equipped monitoring system together with SCFS is suitable for precise management of fertilizer and irrigation application.     

施钾对扬麦158等小麦品种的养分吸收与生物产量的影响

采用田间试验、室内分析与数理统计相结合的方法研究了不同施钾水平对扬麦158在不同生育期体内的氮（N）、磷（P）、钾（K）含量、吸收量及干物质积累量的影响，还比较了同一施肥水平下，扬麦158等7个品种的养分吸收差异。结果表明，拔节-孕穗阶段是小麦养分吸收和生物产量积累的最快时期。不同生育阶段除含磷量较为稳定外，氮、钾变幅大，因此，在制定施肥方案时，应重视氮、钾的合理配合，以满足小麦“高产、优质、高效”生产的营养需要。     

Effects of organic manure and NPK fertilization on earthworm activity in an Oxisol

The effects of fertilization with N, P, K, and organic manure (alone or in combination) on earthworm populations, biomass, and casting activity were measured in a cultivated soil (organic C 1.5%, annual rainfall 2000–2300 mm). These applications of fertilizer caused significant increases in earthworm numbers, biomass, and casts. N alone or in combination with P and K also influenced these earthworm parameters significantly. The inorganic NPK fertilizer in combination with organic manure had a significantly greater effect on earthworm activities than NPK fertilizer alone, and therefore the addition of organic matter appears advisable in order to obtain maximum benefits from NPK fertilizer in this soil.     

长期稻草还田对土壤球囊霉素和土壤C、N的影响

A long-term experiment was conducted to investigate how long-term fertilization and rice straw incorporation into soil affect soil glomalin, C and N. The combined application of chemical fertilizer and straw resulted in a significant increase in both soil easily extractable glomalin （EEG） and total glomalin （TG） concentrations, as compared with application of only chemical fertilizer or no fertilizer application. The EEG and TG concentrations of the NPKS （nitrogen, phosphorus, and potassium fertilizer application ＋ rice straw return） plot were 4.68% and 5.67% higher than those of the CK （unfertilized control） plot, and 9.87% and 6.23% higher than those of the NPK （nitrogen, phosphorus, and potassium fertilizer applied annually） plot, respectively. Application of only chemical fertilizer did not cause a statistically significant change of soil glomalin compared with no fertilizer application. The changes of soil organic C （SOC） and total N （TN） contents demonstrated a similar trend to soil glomalin in these plots. The SOC and TN contents of NPKS plot were 15.01% and 9.18% higher than those of the CK plot, and 8.85% and 14.76% higher than those of the NPK plot, respectively. Rice straw return also enhanced the contents of microbial biomass C （MBC） and microbial biomass N （MBN） in the NPKS plot by 7.76% for MBC and 31.42% for MBN compared with the CK plot, and 12.66% for MBC and 15.07% for MBN compared with the NPK plots, respectively. Application of only chemical fertilizer, however, increased MBN concentration, but decreased MBC concentration in soil.     

Effects of Curtailment of Nitrogen Fertilizer on Biological Properties and Tea Leaf Yield in Acid Tea Field Soils

In Japan, the soils in tea fields are further acidified by heavy application of nitrogen fertilizer. In the long-term fertilizer application fields, available P, total carbon and nitrogen contents had the highest in the Multi-F plot, followed by the 98-D.F plot and the smallest in the 95-D.F plot. Soil enzymes activity had the highest the Multi-F plot. It was estimated that all of the enzyme activity were often corresponded with the results of the organic matter and the available P contents. The number of fungi under acidic condition had the close relation since change of these enzymes activity. It was evident that fungi were participated in carbon, nitrogen and phosphorus metabolism in acid tea field soils. It became clear that the number of fungi and enzymes activity decreased corresponding well with the available P and the organic matter contents depend on fertilization management. Moreover in case of qualities of green tea, generally difference between experimental plots and Multi-F plot were to be small. It was indicated that influence to the yields by curtailment of the amount of nitrogen fertilization was small.     

Effect of fertilizer application on methane emission/production in the paddy soils of Taiwan

Methane production in three types of rice paddy soil was investigated under greenhouse conditions. The amount of methane produced during the first crop season (March to July) was 2–6 times higher than that in the second crop season (August to December). Application of organic fertilizer hastened the drop in redox potential and increased methane production and emission. Methane production also increased with the depth of soil with high values in soil samples from 18 to 30cm depth. Methane production in the first crop season was 18.0, 54.3 and 49.4mgcm^–3 for 6tha^–1 straw application for Linkou, Tzawchyau and Jiaushi soils, respectively. The value was 33.4mgcm^–3 for the second crop season in Jiaushi soil. Methane emission was high during the flowering and maturity stages in the first crop season and the values were high during the tillering and flowering stages in the second crop season. Methane emission was high in Tzawchyau and Jiaushi soils in the first crop season. Methane emission rate reached a maximum from 12 noon to 3p.m. due to high temperature and a minimum at 3 to 6a.m. in both planted and unplanted soils. Received: 17 September 1996     

The Application of Multivariate Statistical Methods for the Evaluation of Soil Profiles (8 pp)

Background, Aim and Scope   Contamination of soils does not only occur on their surface over large areas, but also in depth. Therefore a characterization of soil state after pollution demands a three-dimensional soil sampling, by what a large number of samples has to be analyzed. Analytical results could be evaluated by multivariate statistical methods, which have already been used for the evaluation of data sets containing results from soil sampling of two dimensions like areas or single profiles. In this case study, multivariate statistical methods were applied to investigate structure and interactions between features in a data set containing results of three-dimensional soil sampling. The investigated soil profiles were contaminated by emissions of a former cement and phosphate fertilizer plant. The aim of this study was to determine the remaining extent of contamination and to analyze whether pollutants are mobilized and vertically transported within the profiles. Materials and Methods: Three soil profiles were sampled in the surroundings of the plant. Grain size, organic and carbonatic bonded carbon, pH value, and the total contents of Ca, Cd, Co, Cu, F, Fe, K, Mn, Mg, Na, Ni, P, Pb, and Zn were determined. The resulting data set was evaluated by cluster analysis, linear discriminant analysis, and principal components analysis. The sequential extraction procedure according to Zeien and Brümmer was applied to analyze the binding properties of Ca, Cd, Cu, Na, Pb, and Zn from selected samples. Results: Cd was identified as contaminant of the top soils. The pH values of the bottom soils were determined to be in alkaline range, which is unnaturally high. Variables were clustered according to enrichment of variables in top soils. The samples were classified regarding their pollution state and their substrate by cluster analysis, which was confirmed by linear discriminant analysis. Geogenic and anthropogenic sources of variables as well as relationships between variables like the binding of heavy metals at organic matter were detected by using principal components analysis. The binding of heavy metals at organic matter in the top soils was confirmed by the results of the applied sequential extraction. A vertically altered distribution of Na binding was determined. Discussion: According to the current soil conditions, the uptake of heavy metals had probably occurred by the over ground part of plants during the deposition. The distribution of Na should likely result from the vertical transport of Na, which would also explain the high pH values of the bottom soils by ion exchange. Altogether, the main amount of deposited Ca, F, Na, P, and heavy metals is likely nearly insoluble bound in the top soils. Conclusions: Ten years after the end of production, the pollution of top soils in the surroundings of the former plant is still high. However, regarding the ecotoxicological relevance the now explored interactions between several soil features and elements strongly indicate that there is no short-term to medium-term risk of a mobilization of the deposited elements with the exception of Na. Recommendations and Perspectives: The results of this case study prove that multivariate statistical methods are powerful tools to explore interactions of variables and relationships in a data set derived from three dimensional soil sampling. The methods applied in this work can be highly recommended for evaluations of large data sets resulting from two- or three-dimensional samplings. Multivariate statistical methods enable the characterization of soils and their pollution state in a simple and economic way.     

施肥处理对大肉丝瓜产量和肥料利用的影响

为了更好地了解肥料在大肉丝瓜上的应用效果,在江门进行了不同氮磷钾肥料和有机肥试验.结果表明,氮肥对大肉丝瓜产量和生物量的影响最大,增加有机肥,可以提高前期产量和总产量,肥料的农学效率、偏生产力和利用率在低水平表现较好.通过回归分析,获得肥料效应方程,求得最佳施肥量,大肉丝瓜要获得高产和高效,江门地区推荐每667 m2商品有机肥最佳施肥量为250 kg,氮磷钾最佳施肥量为N 23kg、P2O511 kg、K2O 17 kg.     

连续分期配施有机肥对棉花超高产及土壤肥力的影响

1997～ 1 999年定位施肥试验表明 ,在施N量为 592 5～ 60 0 0kg·hm- 2 (N∶P2 O3∶K2 O =1∶0 5∶0 6) ,有机肥N、P2 O5、K2 O分别占 1 0 0 %～ 1 2 4%、 50 3 %～ 51 0 %和 50 0 %的条件下 ,随着分期配施有机肥年限的增加 ,棉花果节数、结铃数、结铃率和皮棉产量均得到明显的提高 ,铃重和衣分也略有增加 ,土壤肥力也得了改善和提高。创棉花 2 2 50kg·hm- 2 高产 ,要求连续分期配施有机肥 2年以上 ,棉花六成铃区成铃比例皆在 1 0 %以上。     

不同氮钾肥施用方法对水稻产量及抗倒伏性的影响

水稻倒伏常发生于籽粒灌浆中后期,是高产、稳产、优质生产的主要限制因素之一。试验选用寒地超级稻品种松粳9号,研究不同氮钾肥施用方法对水稻产量性状及茎秆抗倒特性的影响,为寒地水稻超高产抗倒栽培技术的建立提供理论依据。结果表明,施氮量为90 kg·hm-2时,增加生育前期氮肥施用量有利于提高单株穗数、每穗粒数和单株粒重,但施氮量为135 kg·hm-2时,减少生育前期氮肥施用量,而提高生育后期氮肥施用量更有利于提高单株穗数、每穗粒数和单株粒重;在同等施氮量条件下,增加生育前期氮肥施用量可极显著增加第1和第2节间长度,并降低茎秆抗折力,尤其是施氮量高时这种影响更大;增加氮肥施用量时,相应增加钾肥施用量和减少生育前期氮肥施用量将有利于提高茎秆抗倒特性;增加生育后期氮肥施用量明显提高茎秆全氮含量,而增加生育前期氮肥施用量有利于促进水稻植株钾的吸收和积累,提高茎秆钾含量;茎秆氮含量与节间长度呈显著或极显著正相关,与抗折力呈负相关;茎秆钾含量与节间长度呈显著负相关,与抗折力呈极显著正相关。