Temporal and Spatial Stability of Soil Test Parameters Used in Precision Agriculture

Abstract

Variable‐rate technology provides crop producers with the opportunity to vary the crop and soil management practices. The objective of this study was to assess the temporal and spatial stability of nitrogen (N), phosphorus (P), potassium (K), zinc (Zn), pH, and soil organic matter (OM) for precision nutrient management. This study was conducted over three growing seasons on a continuous maize (Zea Mays L.) production field in northeastern Colorado, USA. Soil samples were collected using a soil sample grid size of 76.2 m×76.2 m. The field was classified into areas of low, medium, and high productivity potential management zones. Spatial statistical analysis was performed. Measured soil parameters varied significantly over space and time (p<0.01). Management zones were effective in identifying homogenous subregions within the field across time (p<0.01). The data suggest that management zones account for spatial and temporal variability for the various soil parameters evaluated in this study.     

喀斯特山地植烟土壤养分空间变异及分区研究

为揭示喀斯特山地植烟土壤养分空间变异特征并进行分区管理,利用地统计学和模糊C-均值聚类算法对贵州省黔南州喀斯特山地植烟土壤养分进行分析。结果表明,土壤总体呈弱酸性,极小部分土壤缺乏有机质、碱解氮、有效磷、有效铜和有效锌,小部分土壤缺乏速效钾、交换性钙和交换性镁,大部分土壤缺乏有效钼。p H、有机质、碱解氮、有效磷、速效钾、交换性镁、有效铜、有效锌和有效钼空间相关性中等,交换性钙空间相关性弱。p H、有机质、碱解氮、有效磷、速效钾、交换性钙、交换性镁和有效锌空间变异主要由随机因素引起,有效铜和有效钼的空间变异主要由结构性因素引起。土壤养分空间变异趋势效应明显,p H、有效磷、速效钾、交换性钙、交换性镁、有效铜、有效锌和有效钼均由几个高值中心向四周递减分布;有机质和碱解氮均由北部、西部和南部向中部和东部递增分布。研究区植烟土壤可分为4个管理分区,分区内土壤养分趋于同质化,分区间差异显著。本研究为喀斯特山地农田土壤养分管理、农作物平衡施肥和肥料高效利用提供了参考依据。     

新疆察布查尔县农耕层土壤养分空间特征及其与地形因子的关系

[目的]研究土壤养分的空间变异程度、分布规律以及与地形因子间的相关关系,为干旱区绿洲农业的施肥区划、土壤资源的可持续利用及精准农业的推广等提供理论依据。[方法]以新疆伊犁河谷典型绿洲区察布查尔县为研究区,应用GIS技术与地统计学相结合的方法,研究伊犁河谷典型绿洲区农耕层土壤养分的空间分布特征及变异规律,并进一步应用典范对应分析(CCA)技术,对土壤养分空间变异与地形因子的关系进行分析。[结果](1)有机质、碱解氮、速效钾含量的变异系数介于24.22%~46.76%,属于中等变异,而速效磷的变异系数为107.51%,属于强变异;区域内存在中等和较强程度的空间自相关性,且速效钾的空间自相关性稍强,碱解氮的空间自相关性稍弱;(2)土壤养分在空间分布上多呈斑块状。有机质在东部相对含量较低;碱解氮中部含量相对较低且在东西方向上变异较强烈;速效磷在东北和西南方向上相对较低;速效钾在中部偏北和东南方向上相对较低且在东部变异较强烈。(3)碱解氮与高程和地形起伏度呈极显著正相关(p0.01),有机质与坡度、地形起伏度呈显著负相关(p0.05),速效钾与平面曲率、剖面曲率呈正相关关系。(4)高程、坡度、地形起伏度、剖面曲率是影响该区域土壤养分空间分布的主要地形因子。[结论]在今后的农业施肥过程中,适当增加东部有机肥的投入,应适当增加中部氮素的输入,应适当增加东北方向上磷钾元素的注入。     

Characterization of Spatial Variability of Soil Parameters in Apple Orchards of Himalayan Region Using Geostatistical Analysis

ABSTRACT

Knowledge of spatial variability in soil properties is critical for effective nutrient management plan in crop production. Poor productivity of apple orchards in Indian Himalayan Region (IHR) is due to lack of information on the variability of soil properties important for enhancing productivity in the region. The study was conducted in apple orchards with the hypothesis that spatial variability of soil properties is high due to adoption of varied management and passive soil factors. The major objectives of the study were to assess the spatial variability of soil parameters, viz. soil pH, electrical conductivity, soil organic carbon along with plant available soil nitrogen (N), phosphorus (P), potassium (K), exchangeable calcium (Ca), and exchangeable magnesium (Mg) at a regional scale through geostatistical methods. Coefficient of variation (CV) indicated that the fertility parameters varied from medium to high in heterogeneity (CV > 20%). Available N was found critical/medium in 69.6% of soil samples and might be one of the limiting nutrients for crop growth, P and K were in high, and OC in very high range. Significant correlation was found between OC with N; pH with K, Ca and Mg and EC with OC, P and K. The semivariogram parameters indicated that the spatial distribution of soil fertility parameters were inconsistent and showed strong to weak degree of spatial dependence for all parameters. The study highlighted the importance of delineation of soil fertility management zones in the apple growing region as a guide for precise and site-specific nutrient.     

Delineation of Management Zones for Southern Root-Knot Nematode using Fuzzy Clustering of Terrain and Edaphic Field Characteristics

Management zones (MZs) for southern root-knot nematode (RKN) from the integration of terrain (TR) and edaphic (ED) field features might facilitate variable rate nematicide applications. This study was conducted on 11 coastal plain fields in the USA. The relationships between RKN populations and five soil ED and TR attributes (apparent soil electrical conductivity [shallow (EC_a-s) and deep (EC_a-d)], elevation (EL), slope (SL), and changes in bare soil reflectance) were analyzed using canonical correlation. Using two ED and TR data sets, canonical predictors were used for zone delineation. Although the results showed that the zones with RKN population above the RKN field average were associated with the lowest values of EC_a-s, EC_a-d, normalized difference vegetation index (NDVI), and SL with respect to field average values, zone segregation was enough using EC_a-s and EC_a-d data. The results suggest the potential for using soil properties to identify RKN risk zones.     

基于GPS和GIS的田间土壤特性空间变异性的研究

以一块面积约为13.3 hm²的冬小麦田为研究区，利用GPS接收机定位，按50 m×50 m设置网格，共取63个采样点，测定土壤表层(20 cm)内的土壤有机质、全氮、碱解氮、速效磷、速效钾、容重、田间土壤含水率和电导率，研究麦田土壤特性的空间变异规律。采用传统统计学和地统计学相结合的方法对所取的数据进行了分析，利用Arcview3.2软件的空间分析功能，绘制了表达这些土壤特性随机性和结构性的半方差图和空间分布图。研究结果表明：所有土壤特性均服从正态分布；土壤容重具有弱变异强度，其它土壤特性具有中等变异强度；土壤有机质、全氮、碱解氮、速效钾和电导率具有很强的相关性，土壤容重、速效磷和含水率具有中等强度的空间相关性，土壤特性的相关距变化范围为246.8～426.8 m。该成果可为农田的定位施肥、灌溉以及其它的农田精细管理提供依据。     

Spatial Variability of Nutrients in Wheat Plants in Semi-arid Regions of Northwestern Pakistan

This study was undertaken to assess spatial variability of nutrients in wheat plants for variable-rate site-specific fertilizer-management strategy. Wheat plants were collected from two semi-arid regions in northwestern Pakistan during 2004 and analyzed for nutrient contents and spatial variability. Wheat samples from both regions showed widespread deficiency of phosphorus (P), potassium (K), and zinc (Zn). In Kohat, Zn and manganese (Mn) were spatially distributed, described by linear models with moderate spatial patterns, but K, copper (Cu), and iron (Fe) showed weak spatial structures. In Bannu, K was described by a linear model with strong spatial structure and Fe had moderate spatial structure, but P, Cu, Mn, and Zn had random spatial distributions. The maps developed in this study showed variation in plant nutrients and spatial trends in the cases of spatially distributed nutrients and can be used to delineate plant nutrients into low, medium, and high categories to develop variable-rate fertilizer-management strategy.     

黄土丘陵沟壑区退耕地人工柠条林土壤养分特征及其空间变异

应用时空互代方法,以柠条林为例,对黄土丘陵沟壑区不同利用年限人工林土壤养分特征、空间变异及其演变进行了系统的研究。结果表明,该区人工林土壤肥力处于较低水平;人工林表层土壤养分中速效磷和速效钾的空间变异性较大;各环境因子对土壤养分有一定的影响,海拔、坡度和坡向等环境因子与人工林地土壤养分间呈负相关关系,坡位和地形与人工林地土壤养分间呈正相关关系。随着利用年限的增加,人工林土壤养分各指标含量均增加,与利用年限有显著的相关性。有机质、全氮、有效氮和速效磷的增加量不明显,全磷含量保持相对稳定的水平,速效钾经过多年积累有明显的增加。从土壤养分指数模型可以算出该区的人工林土壤有机质、全氮、有效氮约需35a能达到中上等养分水平,速效钾则约需27a才能达到中上等养分水平。     

Site‐specific effects of variable water supply and nitrogen fertilisation on winter wheat

The plant‐available soil water, amount and distribution of rainfall or irrigation are primary factors that may affect yield and quality of winter wheat in heterogeneous fields. The objective of this 2‐y study was to vary N application and water supply in order to achieve a more mechanistic insight into the effects of underlying differences in the site‐specific productivity on heterogeneous fields. Two N fertilizer rates (120 and 180 kg N ha^–1) and three different water supply treatments (rain sheltering, irrigation, rain‐fed) were compared on field sites with lower or higher plant available soil water capacities. On the whole, the site, rather than rainfall or N fertilisation, was the primary factor that accounted for variability in grain yield. Rainfall distribution during the growing season affected the overall yield level in a given year. The sites characterised by lower plant available water capacity did not show higher grain yield and improved quality with the increased N rate. This suggests that the reduced N rate should be recommended on these sites to take into account the environmental sustainability of N fertilisation. With respect to the higher N application at sites of high plant available soil water capacity, although the already high yield levels were not increased further, the protein quality was significantly improved in the first season within all treatments and in the second season in the irrigated treatments. Therefore, a higher N‐rate proved to be advantageous, especially considering that the residual nitrate levels after harvest were low. The study demonstrated that the response of winter wheat to water shortage or abundance and N fertilisation is site‐specific and dependent on the availability of soil water.     

Use of GIS to Delineate Site-Specific Management Zone for Precision Agriculture

Soil heterogeneity is one of the several factors that explain within-field variations in crop yielding. To overcome this problem, an experiment was conducted within the University of Ibadan to identify the zones with similar soil properties that can be managed uniformly to optimize crop yield. A total of 62 soil samples were collected from 6.5 ha of farmland based on the differences in slope, soil moisture regime, land management and cropping pattern. The spatial distributions of soil properties were mapped out using the Inverse Distance Weighing (IDW) interpolation technique and the results were subsequently reclassified into different soil management categories. The results showed that the farmland consists of four classes of total nitrogen (N), phosphorus (P) and soil bulk density (SBD); three classes of carbon (C) and volumetric moisture content (?); two classes of soil _pH; and one class of soil texture. Each of the soil management maps was subsequently overlaid on each other to produce four specific site management units (SSMUs) for vegetable cultivation. The four SSMUs consisted of highly suitable units occupying 0.143 ha, marginally suitable unit occupying 0.971 ha, moderately suitable unit occupying 0.517 ha and unsuitable unit occupying 4.9 ha of land. The SSMUs will alleviate problems of reduced yield due to over- or under-applications of agrochemicals.     

Spatial heterogeneity of soil properties and its mapping with apparent electrical conductivity

The site‐specific cultivation as part of the precision‐agriculture concept is more and more introduced into practical farming. However, soil information is often not available in a spatial resolution intrinsically needed for precision farming or other site‐specific soil use and management purposes. One approach to obtain spatially high‐resolution soil data is the non‐invasive measurement of the apparent electrical conductivity (EC_a). In this study, we recorded the EC_a on three fields with an EM38 (Geonics, Canada). The EC_a data were compared with (1) ground truth data obtained by conventional drilling, (2) traditional soil maps (large scale, ≤1:5,000), (3) the growth and yield of corn. The temporal variability of the EC_a due to varying soil moisture and temperature was taken into account by repeated measurements of the same fields and subsequent averaging of the EC_a values. Significant correlations (r² = 0.76) were found between the mean weighted clay content (0–1.5 m) and the EC_a. Furthermore, in soils with differently textured layers, EC_a was used to estimate the thickness of the uppermost loess layer. A comparison of EC_a and large‐scale soil maps reveals some pros and cons of EC_a measurements. The main advantages of EC_a recordings are the high spatial resolution in combination with low efforts. Yet, the EC_a signal is no direct measure for a soil type or unit. Depending on the variability of substrates and layering, the EC_a pattern can be a precise indicator for the spatial distribution of different soils. A strong conformity of the spatial variability of plant growth (derived from orthophotos and yield maps) and EC_a patterns within a field indicates that the EC_a signal per se—without conversion to traditional soil parameters—integrates the effects of various soil variables that govern soil fertility. Altogether, EC_a surveys can be a powerful tool to facilitate and improve conventional soil mapping.     

农田土壤养分的空间变异性特征

对一块面积为１ｈｍ^２麦田内的９８个观测点取样分析,测定了代表不同土壤含水率水平下的两个时期土壤表层和底层的ＮＨ_４-Ｎ、ＮＯ₃-Ｎ、Ｏｌｓｅｎ-Ｐ、表层有机质和全氮等养分。应用地统计学的方法对所取的数据进行了分析,结果表明底层土壤的ＮＨ_４-Ｎ、表层土壤的有机质服从正态分布;其余养分基本上服从对数正态分布;按一定的精度和置信水平确定了合理的取样数目。通过半方差函数分析,发现这些养分在一定范围内存在空间相关性;采用Ｋｒｉｇｉｎｇ方法对未测点进行了估值,绘制了等值线图,并对两个时期的养分动态的空间变异进行了初步分析。该成果可用于提高氮肥利用率和精确农业（施肥）的研究和实践。     

典型黑土区坡耕地土壤微生物群落数量的空间分布研究

选取土壤侵蚀较严重的黑龙江省宾县宾州河流域为研究区,通过采集流域上、中和下游6个典型坡面的坡上、坡中和坡下部土壤样品,分析了坡耕地土壤微生物群落数量在流域和坡面尺度上的分布规律,并比较了土壤微生物群落数量空间分布与土壤侵蚀空间分布的关系。结果表明,在流域尺度上,土壤微生物总数量和细菌数量均表现为:下游>中游>上游土壤真菌数量表现为:上游>下游>中游土壤放线菌数量表现为中游最大,而上游和下游数量相当。在坡面尺度上,土壤微生物总数量和细菌数量均呈现:坡中部<坡上部<坡下部,土壤真菌数量呈现:坡下部<坡中部<坡上部,土壤放线菌数量呈现:坡中部<坡下部<坡上部。研究表明,流域土壤微生物总数量和土壤细菌数量的空间分布皆与侵蚀-沉积速率的空间分布相对应,反映出侵蚀-沉积速率是影响该流域土壤微生物群落数量的主要因素。     

梁子湖湿地土壤养分的空间异质性

2003年10月利用地统计学方法对梁子湖湿地保护区内一块63.9km2区域的土壤养分的空间变异进行了研究。以400m400m的网格采集了101个表层(015cm)土壤样品。分析结果表明,土壤养分有较大的空间变异,土壤有机质、全氮、全磷、速效氮变异系数分别是36.0%、30.6%1、3.7%和29.3%;速效磷的变异系数最高为50.4%。土壤有机质、全氮、全磷、速效氮和速效磷的理论模型均为球状模型。土壤有机质、全氮、全磷、速效氮具有中等空间自相关性,随机变异分别是68.5%、68.3%、75%和71.5%;速效磷的自空间相关性较弱,变异为82.4%。5种养分的空间自相关距离比较接近,变程在2853m～963m之间。通过克里格插值进行土壤养分空间插值制图显示,土壤养分表现出空间分布的相似性。     

紫色土区小流域土壤保持服务功能的空间分布特征

[目的]分析不同坡度、土壤类型、土地利用下的土壤保持服务功能分布,为减少土壤流失和改进土地利用规划提供科学依据。[方法]结合修正通用土壤流失方程(RUSLE)和GIS技术,以曲水河小流域为典型研究区,基于DEM、土壤、土地利用等基础数据,分析了研究区土壤保持服务功能的分布现状及影响因素。[结果](1)该流域土壤保持总量为1.10×107 t/a,单位面积土壤保持量为384.74t/(hm2·a),具有较高的生态系统服务功能重要性;(2)土壤保持服务功能总体呈现从河谷阶地逐渐向周边丘陵坡地递增的空间分布特征;(3)强烈及以上侵蚀强度区、8°~25°的坡度区、耕地、钙质紫泥田区和红棕紫泥土区应为土壤保持工作的热点区域。[结论]不同坡度、土壤类型、土地利用类型下土壤保持服务功能差异显著,可以通过改良土壤、提高植被覆盖和采取土壤侵蚀防治措施提高土壤保持服务功能水平。     

喀斯特地区烟田土壤养分的空间变异特征

以我国典型的喀斯特地区—贵州省毕节地区为研究区域,利用地统计学和地理信息系统(GIS)相结合的方法对烟田土壤养分的空间变异特征进行研究,皆在为喀斯特地区烟草种植的平衡施肥及生态环境保护提供依据。描述性统计结果表明,研究区烟田土壤各养分指标均属中等程度变异。半方差函数分析表明,研究区烟田土壤全氮、全钾、速效磷变异函数的最适模型是球状模型,全磷和速效钾的最适模型是线性模型,碱解氮、pH和有机质的最适模型为指数模型;速效磷表现为强烈的空间自相关性,主要受结构性因素影响,而全氮、全磷、全钾、碱解氮、速效钾、pH和有机质表现为中等空间相关性,受结构性因素和随机性因素共同影响。普通克里格插值的土壤养分空间分布图表明,研究区域内烟田土壤全氮、全钾、速效磷和速效钾含量分布呈现空间连续分布的特点,而全磷、碱解氮和pH、有机质含量没有明显的分布规律,这主要与喀斯特地区复杂的立地因子和人为影响有关。     

Spatial Distribution of Surface Soil Acidity,Electrical Conductivity,Soil Organic Carbon Content and Exchangeable Potassium,Calcium and Magnesium in Some Cropped Acid Soils of India

Land degradation is a global problem. Best management of degraded land can be done by evaluating the spatial variability of soil properties including chemical properties of degraded land and mapping such variations. Since, a significant portion of arable land in India is chemically degraded due to soil acidity; the present study was conducted to study the spatial variability of soil acidity (pH), electrical conductivity (EC), soil organic carbon (OC) content, exchangeable potassium (K⁺), calcium (Ca²⁺) and magnesium (Mg²⁺) contents in some cropped acid soils of India. A total of four hundred (one hundred from each series) representative surface (0–0.15 m depth) soil samples were collected from arable soils representing four soil series namely Hariharapur, Debatoli, Rajpora and Neeleswaram situated in Orissa, Jharkhand, Himachal Pradesh and Kerala states of India, respectively, and were analyzed. Soil acidity (pH between 3.90 and 6.45) showed a low variability, in contrast to other soil properties, which showed moderate variability. The coefficients of variation varied from 32.4 to 74.3, 31.2 to 50.9, 45.6 to 100, 71.9 to 93.0 and 59.0 to 79.8% for EC (mean between 0.05 and 0.09 dS m⁻¹), OC (mean between 0.29 to 1.86%), exchangeable K⁺ (mean between 39.1 and 77.7 mg kg⁻¹), Ca²⁺ (mean between 148 and 293 mg kg⁻¹) and Mg²⁺ (mean between 111 and 191 mg kg⁻¹), respectively. Soil pH and OC content were positively and significantly correlated with exchangeable K⁺, Ca²⁺ and Mg²⁺ content. Geostatistical analysis revealed that the best fit models were gaussian, exponential and spherical for different soil properties with moderate to strong spatial dependency. Copyright © 2014 John Wiley & Sons, Ltd.     

Using Geostatistics and Geographic Information System Techniques to Characterize Spatial Variability of Soil Properties,Including Micronutrients

Soil properties including micronutrients and their balanced use can significantly affect plant growth and crop production. Hence, the objective of this research was to evaluate the spatial variation of different soil properties including micronutrients in the Dasht-e-Tabriz in the northwest of Iran. Ninety-eight soil sampling sites were selected to collect soil samples from the soil surface layer at a 1000-m distance according to the grid sampling method and analyzed. Soil physical and chemical properties, including the micronutrient concentrations of iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn), were measured. Spatial variabilities of soil properties were determined using the statistical software packages Grow and SPSS. The spatial variabilities of micronutrients in the region were a function of sequenced soil sedimentation, high level of underground water, and the differences in the pedogenesis and hydrological processes. Using such analyses, it is possible to plan appropriate soil management practices, including fertilization.     

广东省典型赤红壤区耕层土壤养分的空间变异

[目的]探讨我国典型赤红壤区——广州市增城区耕层土壤有机质、全氮、有效磷和速效钾含量的空间变异规律,为赤红壤区耕层种植的平衡施肥、水土保持和环境保护提供依据。[方法]利用地统计学方法和地理信息系统技术。[结果]研究区耕层土壤有效磷的含量较高,速效钾的变异系数最大(107.78%),有机质的变异系数最小(32.51%),变异系数由大到小依次为:速效钾有效磷全氮有机质;有机质、全氮具有强烈的各向同性空间自相关性,有效磷与速效钾有着较明显的各向异性空间自相关性;有机质、全氮有着相似的空间分布规律,含量呈东南部高西北低的趋势,有效磷含量处于中上偏高水平,空间分布从北向南呈逐步增多趋势,速效钾空间分布相对比较复杂,各个养分级别都有一定量的分布,总体由北到南逐渐增多。[结论]在一定空间范围内,耕层土壤有机质、全氮、有效磷和速效钾具有不同强度的空间相关性,且选取合适的方向性半方差函数模型能更好地拟合其空间变异情况。