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471.
472.
A field study was conducted to quantify spatial soil variability and to analyze correlations among soil properties at different spatial scales. Soil samples from 0 to 30 cm depth were collected from two adjacent fields in the southwestern Beauce Plain (France) which consisted of Haplic Calcisols and Rendzic Leptosols. Factorial kriging analysis (FKA) was used to describe the co-regionalization of nine soil properties. A linear model of co-regionalization including a nugget effect, and two spherical models were fitted to the experimental data direct and cross-variograms of the topsoil layer properties which were previously estimated. Co-kriged regionalized factors, related to short and long-range variation, were then mapped to characterize soil variation across the two fields. The potential value of ancillary sampled variables, such as yield data, to provide information on soil properties was tested. The relation between yield and measured soil properties appeared to be weak in general. However, the structures of the variation in yield appeared to be relatively stable for two years and showed similar patterns as the co-kriged soil factors. This suggests that information on the scale of variation of soil properties can be derived from yield maps, which can also be used as a guide to suitable sampling interval for soil properties and as a basis for managing fields in a precise way. 相似文献
473.
收集江西一个红壤水稻田长期肥料试验中产量、施肥量、土壤有机碳等资料,结合对农田生产中各项生产资料和管理活动的投入进行调查,对不同施肥处理下系统的生产力、碳投入排放与碳收集效应进行分析,并估算系统的碳汇。评价了不同处理下生产力的碳成本与碳汇效益。结果表明,种植双季稻下化肥配施和化肥有机肥配施下的稻田总碳汇分别为-2．2和-3．2t C·hm^-2·a^-1,但在两季生产中并无显著差异;相应地,有机无机肥配施比纯化肥配方施肥产量提高了30％左右,而碳汇量提高了50％左右。证明有机无机配合施肥是一种可以增产增汇的关键农业生产管理途径。 相似文献
474.
Charles C. Mitchell Gobena Huluka 《Communications in Soil Science and Plant Analysis》2016,47(22):54-63
ABSTRACTPotassium (K) deficiency in crops in southern US Coastal Plain soils has been documented since the l880s. Long-term soil fertility studies such as Alabama’s “Cullars Rotation” experiment (circa 1911) have been conducted with K since 1911. Other Alabama long-term experiments on several Coastal Plain and related Hapludults, Paleudults, and Kandiudults also contain K variable treatments which have been monitored since 1929. Soil test data from these long-term experiments have allowed us to answer some practical questions regarding K dynamics in Coastal Plain soils. Potassium movement through the soil profile is dependent on the soil’s cation exchange capacity (CEC) but relative accumulation is greater in the plow layer regardless of soil CEC. While subsoil K testing may be useful for identifying situations where subsoil K has been depleted, this extra effort and expense is not necessary for most cropping situations. A crop will remove most of its K from the plow layer if it is present in sufficient quantity based on soil test. Crop depletion of plow-layer K to the point where yield may be reduced is gradual and may take 10–15 years or more depending upon soil CEC and initial soil K concentration. Depletion is most rapid in low CEC soils as would be expected. However, soil test K can vary considerably during the course of a crop season with the lowest soil test K concentrations occurring immediately after harvest. 相似文献
475.
《Communications in Soil Science and Plant Analysis》2012,43(9):1237-1246
The estimation of plant-available nitrate nitrogen (NO3-N) is essential for any nutrient-management plan but can be time-consuming and expensive. However, the efficacy of rapid methods to determine soil NO3-N levels designed for grower use has received mixed reviews in the literature. Therefore, the objectives of this study were to (1) evaluate the Cardy electrode-based meter for measuring soil solution NO3-N concentrations under a perennial peanut living mulch in two mixed orchard systems on O'ahu and (2) determine the influence of soil type on measurement accuracy and precision under laboratory conditions. To achieve the first objective, 24 lysimeters were installed 15–30 cm deep at each of two fruit tree orchards with different soils and climate on Oahu island. For the second objective, a replicated column study was conducted, in which NO3-N solutions of varied concentrations were leached through three representative agricultural soils (Wahiawa, Loleka'a, and Waialua series). Field soil solution and column leachate were analyzed using the portable electrode-based meter and a standard laboratory colorimetric method. In the field samples, soil solution NO3-N ranged from <1 to 110 mg/L, and there was a strong correlation (r2?=?0.92) between the portable meter and colorimetric values. Similarly, a strong correlation between the Cardy meter and the laboratory methods was observed in the column study, although r 2 values varied with soil type. The data suggest that the Cardy meter can be used to rapidly and accurately measure soil solution NO3-N, if its concentrations are relatively high and concentrations of interfering ions such as chloride (Cl?) are low. Overall, the primary value of this rapid method may be in estimating relative changes in soil nitrate in response to nutrient management at a single site. 相似文献
476.
Hans‐Werner Olfs Klaus Blankenau Frank Brentrup Jrg Jasper Axel Link Joachim Lammel 《植物养料与土壤学杂志》2005,168(4):414-431
Under‐ as well as overfertilization with nitrogen (N) will result in economic loss for the farmer due to reduced yields and quality of the products. Also from an ecological perspective, it is important that the grower makes the correct decision on how much and when to apply N for a certain crop to minimize impacts on the environment. To aggravate the situation, N is a substance that is present in many compartments in different forms (nitrate, ammonium, organic N, etc.) in the soil‐plant environment and takes part in various processes (e.g., mineralization, immobilization, leaching, denitrification, etc.). Today, many N‐recommendation systems are mainly based on yield expectation. However, yields are not stable from year to year for a given field. Also the processes that determine the N supply from other sources than fertilizer are not predictable at the start of the growing season. Different methodological approaches are reviewed that have been introduced to improve N‐fertilizer recommendations for arable crops. Many soil‐based methods have been developed to measure soil mineral N (SMN) that is available for plants at a given sampling date. Soil sampling at the start of the growing period and analyzing for the amount of NO ‐N (and NH ‐N) is a widespread approach in Europe and North America. Based on data from field calibrations, the SMN pool is filled up with fertilizer N to a recommended amount. Depending on pre‐crop, use of organic manure, or soil characteristics, the recommendation might be modified (±10–50 kg N ha–1). Another set of soil methods has been established to estimate the amount of N that is mineralized from soil organic matter, plant residues, and/or organic manure. From the huge range of methods proposed so far, simple mild extraction procedures have gained most interest, but introduction into practical recommendation schemes has been rather limited. Plant‐analytical procedures cover the whole range from quantitative laboratory analysis to semiquantitative “quick” tests carried out in the field. The main idea is that the plant itself is the best indicator for the N supply from any source within the growth period. In‐field methods like the nitrate plant sap/petiole test and chlorophyll measurements with hand‐held devices or via remote sensing are regarded as most promising, because with these methods an adequate adjustment of the N‐fertilizer application strategy within the season is feasible. Prerequisite is a fertilization strategy that is based on several N applications and not on a one‐go approach. 相似文献
477.
海南省胶园土壤肥力质量指标的时空变异特性研究 总被引：5，自引：1，他引：5
本文利用海南省现有胶园202个0～20cm土壤混合样与海南省现有胶园相应的自然热带雨林、热带灌木草地的第二次全国土壤普查资料中的土壤剖面资料对海南省胶园土壤pH、有机质和NPK等土壤肥力质量指标的时空变异特性作了分析。分析结果表明,植胶后土壤pH、PK水平在时空方向上发生了显著改变。同时,植胶后各地区土壤pH、有机质含量和NPK水平变异系数均发生了不同程度的改变。 相似文献
478.
《Journal of Crop Improvement》2013,27(1):285-302
Summary Mycorrhizae refer to an association (largely symbiotic) between plants and fungi that colonize the cortical root tissue of most agricultural crops during the period of active plant growth. The contribution of these symbioses to plant growth and soil fertility maintenance has been well-recognized for past several years. In spite of these benefits to agriculture, at present, the realization of the full potential of these fungi has not yet been reached. It must also be recognized that recent research on the possible application of the mycorrhizal symbiosis in agriculture has revealed many gaps in knowledge of fungal biology and ecology. Scientific knowledge on the role of these fungi in plant development and protection, soil stabilization, aggregate formation and creation of nutrient reserves is still limited. For efficient use and manipulation of these fungal symbioses for long-term agricultural stability and productivity, our understanding of their physiology, function and interactions with existing crops and environmental conditions should be improved. Besides, effects of different agronomic practices, application of chemical fertilizers and pesticides on their ecology and function should be elucidated before their successful utilization in agriculture. This paper presents information on the morphology of different my-corrhizal fungi, their physiology and functions. Methods presently used to produce mycorrhizal inocula, their application in the field, problems to be resolved for their massive exploitation and future research needs have also been described. References have been selected to explain the recent advances in our understanding on these beneficial fungi. 相似文献
479.
采用径流场结合人工模拟降雨方式,研究了海南岛万泉河、南渡江和昌化江三大流域土壤中氮、磷、有机质等营养物质的流失特征。结果表明,三大流域土壤径流系数和泥沙流失速率的大小顺序为：暴雨〉大雨〉中雨;相同雨强条件下,万泉河的径流系数与南渡江相近,昌化江最小;泥沙流失速率大小顺序为：万泉河〉南渡江〉昌化江;雨强对总磷（TP）流失速率的影响达到极显著水平,磷随径流流失以颗粒磷（PP）为主;氮在雨强较小时以可溶氮（DN）流失为主,当达到暴雨时则以颗粒氮（PN）流失为主;雨强越大,地表径流中COD、TN、DN和PN流失速率越高。三大流域区土壤养分随泥沙流失特征相似,不同雨强条件下,三大流域的总氮、总磷和有机质流失速率的规律一致,雨强越大,流失速率越高;在同一雨强条件下,三流域区总氮、总磷和有机质随泥沙流失速率为：昌化江〉万泉河〉南渡江。影响面源流失的主要因素为坡度、雨强、土质等。 相似文献
480.
在开放式空气O3浓度增加（FACE）平台下,采用盆栽试验,初步研究了O3浓度升高后麦田重金属Cu的生物有效性变化以及对各生长阶段小麦叶片生理毒性的影响。结果表明,在FACE条件下,小麦地上部对Cu的吸收相比于正常大气对应组有增加的现象;与正常大气对应组相比,FACE条件下土壤中有效态Cu的含量也有所增加;随着小麦的生长发育,FACE圈小麦叶片内的MDA含量总体呈上升趋势,O3升高铜污染组的小麦叶片内MDA的含量最高;与正常大气对照组相比,O3升高铜污染组的小麦叶片SOD酶和POD酶比较敏感,在分蘖期其活性受到诱导,但随着暴露时间的增加,抗氧化系统的各个酶的活性逐渐受到抑制。O3加剧了Cu对小麦的牛理胁迫．增加了Cu的牛物有效性。 相似文献