The delineation of agricultural management zones with high resolution remotely sensed data

Remote sensing (RS) techniques have been widely considered to be a promising source of information for land management decisions. The objective of this study was to develop and compare different methods of delineating management zones (MZs) in a field of winter wheat. Soil and yield samples were collected, and five main crop nutrients were analyzed: total nitrogen (TN), nitrate nitrogen (NN), available phosphorus (AP), extractable potassium (EP) and organic matter (OM). At the wheat heading stage, a scene of Quickbird imagery was acquired and processed, and the optimized soil-adjusted vegetation index (OSAVI) was determined. A fuzzy k-means clustering algorithm was used to define MZs, along with fuzzy performance index (FPI), and modified partition entropy (MPE) for determining the optimal number of clusters. The results showed that the optimal number of MZs for the present study area was three. The MZs were delineated in three ways; based on soil and yield data, crop RS information and the combination of soil, yield and RS information. The evaluation of each set of MZs showed that the three methods of delineating zones can all decrease the variance of the crop nutrients, wheat spectral parameters and yield within the different zones. Considering the consistent relationship between the crop nutrients, wheat yield and the wheat spectral parameters, satellite remote sensing shows promise as a tool for assessing the variation in soil properties and yield in arable fields. The results of this study suggest that management zone delineation using RS data was reliable and feasible.     

A comparison of different algorithms for the delineation of management zones

One approach to the application of site-specific techniques and technologies in precision agriculture is to subdivide a field into a few contiguous homogenous zones, often referred to as management zones (MZs). Delineating MZs can be based on some sort of clustering, however there is no widely accepted method. The application of fuzzy set theory to clustering has enabled researchers to account better for the continuous variation in natural phenomena. Moreover, the methods based on non-parametric density estimation can detect clusters of unequal size and dispersion. The objectives of this paper were to: (1) compare different procedures for creating management zones and (2) determine the relation of the MZs delineated with potential yield. One hundred georeferenced point measurements of soil and crop properties were obtained from a 12 ha field cropped with durum wheat for two seasons. The trial was carried out at the experimental farm of CRA-CER in Foggia (Italy). All variables were interpolated on a 1 × 1 m grid using the geostatistical techniques of kriging and cokriging. The techniques compared to identify MZs were: (1) the ISODATA method, (2) the fuzzy c-means algorithm and (3) a non-parametric density algorithm. The ISODATA method, which was the simplest, subdivided the field into three distinct classes of suitable size for uniform management, whereas the other two methods created two classes. The non-parametric density algorithm characterized the edge properties between adjacent clusters more efficiently than the fuzzy method. The clusters from the non-parametric density algorithm and yield maps for three seasons (2005–2006, 2006–2007 and 2007–2008) were compared and agreement measures were computed. The kappa coefficients for the three seasons were negative or small positive values which indicate only slight agreement. These results illustrate the importance of temporal variation in spatial variation of yield in rainfed conditions, which limits the use of the MZ approach.     

双季稻田冬种对土壤肥力的影响及相关性分析

通过大田试验,对比研究了"冬闲-双季稻"和不同的"冬种-双季稻"种植模式对土壤肥力的影响。结果表明:与冬闲-双季稻种植模式相比,冬种-双季稻种植模式的土壤容重均有一定程度的下降,其中冬种大麦模式的降低幅度最大;所有冬种-双季稻种植模式的土壤有机质、全氮、全磷、全钾及速效钾含量都有一定的增加,但冬种豌豆模式的土壤速效氮和有效磷含量降低了。综合全部指标来看,稻田冬季种植蚕豆模式增加土壤养分含量最明显。     

淹水条件对稻田土壤肥力及理化性质的影响研究进展

笔者归纳综述了湖南省6种典型的稻田土壤类型及其成土母质,分析了淹水条件对土壤肥力及理化特性的影响,并探讨了高产土壤改良的策略,以期为湖南省高产稻田土壤的立地条件和主要肥力特性提供理论依据.     

Geostatistical modelling of within-field soil and yield variability for management zones delineation: a case study in a durum wheat field

The paper proposes a geostatistical approach for delineating management zones (MZs) based on multivariate geostatistics, showing the use of polygon kriging to compare durum wheat yield among the different MZs (polygons). The study site was a durum wheat field in southern Italy and yield was measured over three crop seasons. The first regionalized factor, calculated with factorial cokriging, was used to partition the field into three iso-frequency classes (MZs). For each MZ, the expected value and standard deviation of yield were estimated with polygon kriging over the three crop seasons. The yield variation was only in part related to soil properties but most of it might be ascribable to different patterns of meteorological conditions. Both components of variation (plant and soil) in a cropping system should then be taken into account for an effective management of rainfed durum wheat in precision agriculture. The proposed approach proved multivariate Geostatistics to be effective for MZ delineation even if further testing is required under different cropping systems and management.     

豆科绿肥及施氮量对旱地麦田土壤主要肥力性状的影响

通过2a田间定位试验,研究渭北旱塬地区夏闲期插播并翻压不同豆科绿肥(长武怀豆、大豆和绿豆)以及小麦生长季不同施氮量(0,108,135,162 kg/hm2)对麦田土壤肥力性状的影响,以期为提高旱地土壤质量提供理论依据.试验结果表明:(1)种植豆科绿肥能显著提高土壤有机质、活性有机质和全氮含量,增加土壤碳库管理指数(CPMI),对土壤速效钾含量没有显著影响;(2)绿豆还田量高于长武怀豆和大豆,然而土壤培肥效果逊于长武怀豆和大豆;(3)夏闲期种植绿肥明显消耗了土壤水分,导致绿肥翻压前、小麦播前直至收获后,0-200 cm土壤贮水量显著低于休闲处理,但耗水量与休闲没有明显差异,由于小麦产量显著增加,因此豆科绿肥显著提高了水分生产效率;(4)与不施氮相比,小麦生长季施用氮肥能显著增加土壤水分生产效率,却对土壤各肥力性状的影响均不显著.夏闲期种植并翻压豆科绿肥是旱地培肥土壤、提高水分生产效率的有效途径.     

带籽紫云英翻耕对水稻产量及稻田土壤性质的影响（英文）

[目的]研究带籽紫云英作为绿肥对稻田土壤性质的影响,为推进绿肥生产和农田可持续利用提供依据。[方法]开展3年田间定位实验,第1年设置4个不同紫云英翻压量（2.81,5.61,8.42,11.23 t/hm2）处理,无紫云英翻压作对照处理,后两年均延续上一年实验结果,每年水稻移栽前将各个小区田面自然长出的带籽紫云英测产后直接翻耕;测定水稻产量及稻田土壤养分、生物学性质以及水稳性团聚体等指标。[结果]紫云英带籽翻耕的绿肥处理可使水稻有效穗及产量显著增加,并增加土壤中的有机酸,同时土壤磷酸酶、蔗糖酶和过氧化氢酶等活性均明显提高;土壤水溶性有机酸随绿肥施用量增加而升高,但过多绿肥使用量会抑制土壤微生物量碳;土壤由大团聚体和微团聚体向中微团聚体富集。[结论]带籽紫云英作为绿肥施用能起到改善土壤理化性质和生物学性质,稳步提高土壤肥力,显著增加水稻产量的作用,水稻移栽前翻压量以不超过8.42 t/hm2（干重）为宜。     

Data fusion techniques for delineation of site-specific management zones in a field in UK

Fusion of different data layers, such as data from soil analysis and proximal soil sensing, is essential to improve assessment of spatial variation in soil and yield. On-line visible and near infrared (Vis–NIR) spectroscopy have been proved to provide high resolution information about spatial variability of key soil properties. Multivariate geostatistics tools were successfully implemented for the delineation of management zones (MZs) for precision application of crop inputs. This research was conducted in a 18 ha field to delineate MZs, using a multi-source data set, which consisted of eight laboratory measured soil variables (pH, available phosphorus (P), cation exchange capacity, total nitrogen (TN), total carbon (TC), exchangeable potassium (K), sand, silt) and four on-line collected Vis–NIR spectra-based predicted soil variables (pH, P, K and moisture content). The latter set of data was predicted using the partial least squares regression (PLSR) technique. The quality of the calibration models was evaluated by cross-validation. Multi-collocated cokriging was applied to the soil and spectral data set to produce thematic spatial maps, whereas multi-collocated factor cokriging was applied to delineate MZ. The Vis–NIR predicted K was chosen as the exhaustive variable, because it was the most correlated with the soil variables. A yield map of barley was interpolated by means of the inverse distance weighting method and was then classified into 3 iso-frequency classes (low, medium and high). To assess the productivity potential of the different zones of the field, spatial association between MZs and yield classes was calculated. Results showed that the prediction performance of PLSR calibration models for pH, P, MC and K were of excellent to moderate quality. The geostatistical model revealed good performance. The estimates of the first regionalised factor produced three MZs of equal size in the studied field. The loading coefficients for TC, pH and TN of the first factor were highest and positive. This means that the first factor can be assumed as a synthetic indicator of soil fertility. The overall spatial association between the yield classes and MZs was about 40 %, which reveals that more than 50 % of the yield variation can be attributed to more dynamic factors than soil parameters, such as agro-meteorological conditions, plant diseases and nutrition stresses. Nevertheless, multivariate geostatistics proved to be an effective approach for site-specific management of agricultural fields.     

底栖鱼类对水田土壤微生物的扰动效应（摘要）

[目的]研究底栖鱼类泥鳅对水田土壤微生物（区系、生物量、生理群）的扰动效应。[方法]通过田间定位定量试验,采用平板表面涂抹法和稀释法进行分析。[结果]试验水田的土壤微生物区系组成中,细菌数量最多,其次是放线菌和真菌。养鱼水田的细菌、放线菌和真菌数量均高于对照水田,分别达到显著（P〈0.05）、极显著（P〈0.01）、极显著差异水平（P〈0.01）。养鱼水田的土壤微生物生物量C和N明显高于对照水田,均达到极显著差异水平（P〈0.01）;养鱼水田的土壤微生物生物量P也高于对照水田,但并未达到显著差异水平（P〉0.05）。底栖鱼类促进了土壤固氮菌、纤维素分解菌、硝化细菌、硫化细菌和氨化细菌的生长,抑制了反硝化细菌和反硫化细菌的繁殖。[结论]底栖鱼类对水田土壤微生物区系、生物量和生理群具有重要影响,改善了土壤微生物的生存条件,提高了土壤肥力和生化活性,有助于增加土壤N、P、S等养分元素的供给能力和养分利用效率。     

红花草压青对水稻产量的影响

冬种绿肥(红花草)不仅能培肥土壤、改造中低产田、实现高产稳产农田,也是发展农业的重要措施。本试验结果表明:绿肥压青能促进水稻和生长发育,提高稻谷产量,在中低肥力的田块以红花草压青30000公斤/公顷为宜。     

底栖鱼类对水田土壤微生物的扰动效应

[目的]研究底栖鱼类泥鳅对水田土壤微生物（区系、生物量、生理群）的扰动效应。[方法]通过田间定位定量试验,采用平板表面涂抹法和稀释法进行分析。[结果]试验水田的土壤微生物区系组成中,细菌数量最多,其次是放线菌和真菌。养鱼水田的细菌、放线菌和真菌数量均高于对照水田,分别达到显著（P〈0.05）、极显著差异水平（P〈0.01）。养鱼水田的土壤微生物生物量C和N明显高于对照水田,均达到极显著差异水平（P〈0.01）;养鱼水田的土壤微生物生物量P也高于对照水田,但未达显著差异水平（P〉0.05）。底栖鱼类促进了土壤固氮菌、纤维素分解菌、硝化细菌、硫化细菌和氨化细菌的生长,抑制了反硝化细菌和反硫化细菌的繁殖。[结论]底栖鱼类对水田土壤微生物区系、生物量和生理群具有重要影响,改善了土壤微生物的生存条件,提高了土壤肥力和生化活性,有助于增加土壤N、P、S等养分元素的供给能力和养分利用效率。     

轮作制度对农田氧化亚氮排放的影响及驱动因子

 于2003年6月至2004年5月进行田间试验，2003年夏种植大豆、玉米和水稻，后季种植冬小麦。观测项目包括农田N2O排放、土壤温度、湿度及生物学因子。观测结果表明，在不同的轮作方式中，玉米（施氮）-小麦（施氮）轮作农田的N2O年度排放量最高，为(18.5±0.7)kgN·ha-1；大豆（不施氮）-小麦（施氮）处理次之，为（13.2±0.4）kgN·ha-1；水稻（施氮）-小麦（施氮）轮作最低，为（11.7±0.7）kgN·ha-1，三者之间存在极显著差异（P =0.001）。相对于耕翻处理，稻茬麦田播前免耕在冬前促进了N2O排放（P＜0.001），但并未增加季节性排放总量(P＞0.1)。大豆、玉米、水稻、小麦田N2O通量的自然对数值（y）与土壤温度（T）、湿度（W）和叶面积指数（L）的关系可用逐步回归方程y=a·W＋b ·T＋c·L＋d表示（a、b、c、d为回归系数），其中玉米田y与L关系不明显，c值为0；大豆田y与W、T关系不显著，a=0，b=0；灌溉稻田a值为0，且y与L关系不明显。大豆、水稻、小麦田N2O通量均与生态系统呼吸速率呈极显著正相关关系（P＜0.0001），而玉米田不存在类似关系。     

冬季覆盖植物对南方稻田土壤养分和水稻生长的影响

以冬闲-双季稻为对照,通过对黑麦草-双季稻、紫云英-双季稻、油菜-双季稻和马铃薯-双季稻等5种不同冬季覆盖植物稻田土壤养分变化及晚稻生长进行为期4年的定位研究.结果表明:不同冬季覆盖植物均能改善稻田土壤肥力状况,提高稻田土壤有机碳和全氮的含量,促进晚稻对养分的吸收和植株生长发育.晚稻植株的根系和地上部分干物质积累量均明显高于对照;上述4种冬季覆盖植物晚稻的有效穗数分别比对照增加23.36,21.24,11.19,31.86万/hm~2,其穗长、穗重和结实率与对照均无明显差异,千粒重分别比对照增加0.11,0.95,0.13,0.51g;油菜-双季稻晚稻的穗干重明显高于对照及其它处理.稻田冬季覆盖植物有利于改善晚稻产量构成因素,不同程度地提高水稻产量,分别比对照增加649.67,558.64,437.26,783.82kg/hm~2.     

Evaluation of an analytical method to identify determinants of rice yield components and protein content

Modern information technologies have facilitated the collection of data to assess various aspects of rice production such as yield, quality, soil properties and growth conditions. Currently, farmers can identify any variation of these indicators within a field, between fields or with other farmers. However, a comprehensive analytical method to identify the determinants of variability has not been developed, and the data collected are not efficiently utilized to diagnose and improve the production skills of farmers. Our study focused on the development of an analytical method that can identify the determinants of rice yield and quality. The analytical method used applied cluster analysis (Ward method) to assess the data from 82 paddy fields where rice is produced in various environments and with various management styles. Initially, the 82 paddy fields were classified into 11 clusters based on five indicators of yield components and rice quality; number of panicles, number of spikelets, percentage of ripened grains, 1000-grain weight (GW) and protein content of brown rice. Then, 9 of 11 clusters (two clusters were excluded due to insufficient data to form a cluster) were divided into four groups based on yield capacity. As a result, common characteristics of fertilizer application, meteorological environment and growth conditions were extracted from each cluster. Furthermore, determinants of yield components and protein content were efficiently identified based on the common characteristics extracted.     

稻草还田和冬种绿肥对华南双季稻产量及稻田CH4排放的影响

以常规稻合丰占为材料,开展田间裂区试验,主因素设稻草不还田和全部稻草还田2种处理,副因素设冬闲和冬种绿肥并全部还田2种处理,研究稻草还田和冬种绿肥及其互作对华南双季稻产量和稻田CH4排放的影响,以期为华南双季稻低碳高产栽培提供指导。结果表明:稻草全量还田显著提高水稻产量,平均增产4.8%,主要原因是稻草还田促进水稻的干物质积累,增加了每穗粒数,但稻草还田极显著增加稻田CH4排放量,平均增幅为41.8%;冬种紫云英绿肥显著提高水稻产量,平均增产3.6%,同时稻田CH4排放量也增加,但差异没有达到显著水平。无论是对水稻产量还是稻田CH4排放,稻草还田和冬种绿肥处理之间的互作效应均不显著,表明二者的作用是相互独立的。综合考虑水稻产量和CH4排放的表现,冬种紫云英绿肥可作为华南双季稻低碳高产栽培的重要措施。     

不同养分管理模式与耕作栽培措施对作物产量和土壤肥力的影响

[目的]为快速提高中低产田肥力和农田生产力提供理论依据。[方法]通过田间试验研究了不同栽培管理模式（农民习惯耕作栽培与高产栽培管理模式）和养分管理模式（传统养分管理模式和高效养分管理模式）对冬小麦/夏玉米轮作体系中作物产量和土壤肥力的影响。[结果]在高产高效管理模式下,作物产量显著高于农民习惯管理模式。经过5季作物的试验,高产高效管理模式的农田有机质含量提高了2.72～3.01 g/kg,土壤全氮含量升高了0.12～0.16 g/kg,速效磷（O lsen-P）含量增加了5.2 mg/kg,速效钾含量升高了37.8 mg/kg。[结论]综合考虑作物产量和土壤肥力,高产高效管理模式是中低产农田作物产量提高和耕地地力提升的有效途径。     

不同养分管理模式与耕作栽培措施对作物产量和土壤肥力的影响

[目的]为快速提高中低产田肥力和农田生产力提供理论依据。[方法]通过田间试验研究了不同栽培管理模式（农民习惯耕作栽培与高产栽培管理模式）和养分管理模式（传统养分管理模式和高效养分管理模式）对冬小麦/夏玉米轮作体系中作物产量和土壤肥力的影响。[结果]在高产高效管理模式下,作物产量显著高于农民习惯管理模式。经过5季作物的试验,高产高效管理模式的农田有机质含量提高了2.72～3.01g/kg,土壤全氮含量升高了0.12～0.16g/kg,速效磷（Olsen-P）含量增加了5.2mg/kg,速效钾含量升高了37.8mg/kg。[结论]综合考虑作物产量和土壤肥力,高产高效管理模式是中低产农田作物产量提高和耕地地力提升的有效途径。     

不同利用方式对紫色水稻土微生物量碳的影响

通过研究西南大学试验农场包括不同的耕作、轮作和施肥的综合利用方式对经14年28茬的中性紫色水稻土壤微生物量碳的差异,探究利用方式对紫色水稻土生物活性的影响。结果表明:耕层土壤微生物量碳主要介于200～600mg/kg,除垄作耕翻(稻油)处理外,基本随深度增加而降低。长期垄作免耕并实行稻油轮作的利用方式使其土壤微生物量碳在0～10cm土层与其他利用方式相比明显增加,并且差异显著;而水旱轮作(稻油)的利用方式不利于增加微生物量碳,说明微生物量碳可用作利用方式影响紫色水稻土土壤质量变化的生物学评价指标。从提高土壤生物活性与有机碳含量的角度来看,垄作免耕(稻油)的利用方式最适合于紫色水稻土。     

带籽紫云英翻耕对水稻产量及稻田土壤性质的影响

【目的】研究带籽紫云英作为绿肥对稻田土壤性质的影响,为推进绿肥生产和农田可持续利用提供依据。【方法】开展3年田间定位试验,第一年设置4个不同紫云英翻压量（2.81,5.61,8.42,11.23 t/ha）处理,无紫云英翻压作对照处理,后两年均延续上一年试验结果,每年水稻移栽前将各小区田面自然长出的带籽紫云英测产后直接翻耕;测定水稻产量及稻田土壤养分、生物学性质以及水稳性团聚体等指标。【结果】紫云英带籽翻耕的绿肥处理可使水稻有效穗及产量显著增加,并增加土壤中的有机酸,同时土壤磷酸酶、蔗糖酶和过氧化氢酶等活性均明显提高;土壤水溶性有机碳随绿肥施用量增加而升高,但过多绿肥施用量会抑制土壤微生物量碳;土壤由大团聚体和微团聚体向中微团聚体富集。【结论】带籽紫云英作为绿肥施用能起到改善土壤理化性质和生物学性质,稳步提高土壤肥力,显著增加水稻产量的作用,水稻移栽前翻压量以不超过8.42 t/ha（干重）为宜。     

水分管理影响稻田甲烷排放研究进展

水分管理是影响稻田甲烷(CH4)产生、氧化与排放的重要因素之一.根据国内外文献资料,综述了非水稻生长期和水稻生长期水分管理对稻田CH4产生排放的影响,以及非水稻生长期水分管理对水稻生长期CH4产生排放的影响,并提出有待研究的内容.综合多年的研究结果表明,冬季淹水不仅引起冬季(非水稻生长期)CH4的大量排放,还影响水稻生长期CH4排放量.非水稻生长期土壤水分含量越高,随后水稻生长期CH4排放量越大,产生和氧化能力越强.水稻生长期烤田相对于持续淹水能大量减少CH4排收.