Bodenvariabilität und Verhalten von Pflanzenschutzmitteln

Soil variability and pesticide behaviour The spatial variability of selected soil characteristics (organic carbon, particle size), pesticide adsorption and leaching was estimated for an agricultural location. Variograms were calculated to describe the spatial dependence of data. All parameters showed a nearly isotropic behaviour. According to variograms a kriging interpolation was done and the spatial variability of parameters was estimated. Leaching of terbuthylazine was calculated (model PRZM) with regard to soil variability and adsorption pattern (K_d-values). Leaching depth in the winter season varied between 10 and 22 cm depending strictly on soil characteristics.     

Effects of soil-cation composition on reactions of four herbicides in a candler fine sand

Sorption, persistence and transport of herbicides in soils depend on the relative saturation of soils with cations from various soil amendments. Current research was conducted to study the effect of preequilibration of a Candler fine sand (Hyperthermic uncoated typic Quartzipsamments; 0–30 cm depth) with AlCl₃, CaCl₂, CuCl₂, FeCl₃, or KCl salt solutions on sorption in bromacil, simazine, norflurazon, and diuron herbicides commonly used in Florida citrus groves. Preequilibration of the soil with either FeCl₃, or AlCl₃ significantly decreased the sorption and therefore increased internal leaching potential, of all four herbicides as compared to their sorption in untreated soil. This decrease in sorption was much greater for bromacil and simazine (24 to 35%) than for norflurazon and diuron (7 to 8%). The desorption of bromacil and diuron in 1M NH₄OAc was also significantly lower in soils preequilibrated with FeCl₃ or AlCl₃ than the untreated soil. However, the reverse was true in the case of simazine and norflurazon. Preequilibration of the soil with CuCl₂, KCl, and CaCl₂ resulted in a significant decrease in sorption of norflurazon, diuron, and simazine but did not affect bromacil sorption. Accordingly, the species of adsorbed cation had varying effects on the sorption/desorption of each of the herbicides and varied their leaching potential.     

大型喷灌条件下马铃薯田间土壤含水率空间变异特征及合理采样数研究

[目的]研究马铃薯田间不同深度土壤含水率的空间分布规律及其合理采样数,为大型喷灌条件下精准灌溉制度的制定提供科学依据。[方法]在约34 hm~2的农田中采用固定与随机相结合的方法布设了116个取样点,分别测定了0—20 cm和20—40 cm深度的土壤含水率,采用经典统计学与地统计学相结合的方法,研究喷灌前后马铃薯生长期内土壤含水率的空间分布特征及其合理采样数。[结果] 0—20 cm深度灌溉前和灌溉后的平均土壤含水率的变化范围7.61%～13.79%,20—40 cm深度灌溉前和灌溉后的平均土壤含水率的变化范围为8.71%～16.12%;总体上土壤含水率变异系数变化范围为16.47%～28.55%,均表现为中等程度的变异性,20—40 cm深度的土壤含水率变异程度略高于表层。连续2 a马铃薯各时期土壤含水率总体表现为中等程度的空间相关性,土壤含水率空间变异受随机因素与结构因素共同影响。田间水分总体上呈斑块状分布,灌水后期土壤含水率的分布较灌前更为分散。地统计学得出田间合理采样数为87个。[结论]在大型喷灌条件下马铃薯田间土壤含水量存在中等程度的空间变异性,并且地统计学与传统统计学两种方法均适用于确定农田平均土壤含水率的最优采样数量。     

肥料氮的淋溶深度对肥效的影响

在人工模拟土柱中,用~(15)N示踪方法,研究了麦田追施尿素之后,随灌溉水淋溶到不同深度层次中的肥料氮对小麦的有效性及其再分布规律。结果表明,肥料氮的淋溶深度对其有效性确有一定影响,在0～40cm内,这一影响不显著,而在达到40cm以下时,肥料氮的利用率降低7.22％～12.36％,肥效下降13.99％～22.49％,达极显著水平。植株吸收肥料氮的比例随着淋溶深度的加深而有所降低。淋溶到土体深处的肥料氮的再分布能力很弱。肥料氮的损失率与利用率成反相关。     

Fate of diuron and terbuthylazine in soils amended with two-phase olive oil mill waste

The addition of organic amendments to soil increases soil organic matter content and stimulates soil microbial activity. Thus, processes affecting herbicide fate in the soil should be affected. The objective of this work was to investigate the effect of olive oil production industry organic waste (alperujo) on soil sorption-desorption, degradation, and leaching of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] and terbuthylazine [N2-tert-butyl-6-chloro-N4-ethyl-1,3,5-triazine-2,4-diamine], two herbicides widely used in olive crops. The soils used in this study were a sandy soil and a silty clay soil from two different olive groves. The sandy soil was amended in the laboratory with fresh (uncomposted) alperujo at the rate of 10% w/w, and the silty clay soil was amended in the field with fresh alperujo at the rate of 256 kg per tree during 4 years and in the laboratory with fresh or composted alperujo. Sorption of both herbicides increased in laboratory-amended soils as compared to unamended or field-amended soils, and this process was less reversible in laboratory-amended soils, except for diuron in amended sandy soil. Addition of alperujo to soils increased half-lives of the herbicides in most of the soils. Diuron and terbuthylazine leached through unamended sandy soil, but no herbicide was detected in laboratory-amended soil. Diuron did not leach through amended or unamended silty clay soil, whereas small amounts of terbuthylazine were detected in leachates from unamended soil. Despite their higher sorption capacity, greater amounts of terbuthylazine were found in the leachates from amended silty clay soils. The amounts of dissolved organic matter from alperujo and the degree of humification can affect sorption, degradation, and leaching of these two classes of herbicides in soils. It appears that adding alperujo to soil would not have adverse impacts on the behavior of herbicides in olive production.     

单次污水灌溉后长期污灌土壤镉的垂向分布特征

以河南省新乡市娘娘庙污灌区一块约328 m2的田块为研究区,采用均值、变异系数、半方差函数及分维数等相结合的方法,分析一次污水灌溉前后10 d内东西向剖面A、B、C和D(南北向每相距10.5 m设置1个剖面,由北至南依次编号为A、B、C和D)的土壤有效镉的垂向空间变异及其分布特征,为田块土壤中有效态镉分布与土壤植物修复相结合的研究思路提供基础性探讨。结果表明:灌水后,土壤有效镉含量在剖面A、B、C和D的均值分别减少0.06 mg?kg?1、0.11 mg?kg?1、0.14 mg?kg?1和0.23 mg?kg?1,呈现中等离散程度;在0.393~1.308 m变程范围内,块基比C0/(C0+C)25%,土壤有效镉剖面总体表现出由随机性引发的变异较小,空间相关性较强;剖面A、C和D土壤有效态镉的分维数降低,空间变异程度减弱。Kriging插值结果表明该区有效镉呈条带状分布格局,且在0~15 cm土层呈现累积现象;沿灌水方向,土壤有效镉含量剖面等值线分布由密集到稀疏。相关分析表明,土壤有效镉含量与土壤有机质含量呈正相关,与土壤含水率呈中等程度相关,与p H呈现强负相关,表现为土壤有机质含量越高土壤有效镉含量越大,p H越高土壤有效镉含量越小;污水灌溉对土壤有效镉、土壤含水率、土壤p H和土壤有机质的影响显著,同时会削弱有效镉与各影响因子间的相关关系。伴随着污水灌溉动态的有效镉分布和变异特征可以为应用植物吸附进行土壤重金属污染修复方面的研究提供基础数据。     

Soil penetrometer resistance spatial variability in a Ferralsol at several soil moisture conditions

The penetrometer resistance (PR) spatial variability in a Ferralsol under different soil moisture conditions was characterized through statistical and geostatistical methods. PR measurements were made in a 10-row, 10-columns, 3-m spacing grid at 20–30 cm depth using a hand-pushing penetrometer. Measurements were made for dry soil conditions (before irrigation) as well as 2 and 24 h after irrigation. The soil bulk density (BD) and the relative topographical altitudes (RT) were measured at the same locations. The PR spatial variability is normally distributed for dry soil conditions and after irrigation-water redistribution. A normal distribution fits also to the BD spatial variability. PR mean and coefficients of variations are lower for wet soil conditions and vary notably according to the soil moisture condition. The PR semivariance values are much higher for dry soil conditions than those found for wet soil conditions. However, the semivariogram of PR before irrigation shows almost a pure nugget effect. Irrigation yields a spatial structure in PR measurements. Despite the differences in the shown spatial structure, the range of the PR semivariograms before and 24 h after irrigation is about 8–10 m, which is very similar to the range of the BD semivariogram. The correlation coefficients between PR and the other measured variables are very small before and after irrigation, which could lead to the conclusion that those variables are not related at all. However, according to the co-dispersion coefficients plotted as a function of the separation lag, the correlation between those variables changes according to the separation distance. Particularly, PR and the RT show correlation 24 h after irrigation only for lags between 5 and 12 m. The results pointed out that PR spatial variability depends on soil moisture condition, soil BD and on several local features as microtopography.     

Influence of four soil maintenance practices on Collembola communities in a Mediterranean vineyard

We studied the influence of four soil maintenance practices on Collembola communities in the soil of a Mediterranean vineyard: (a) postemergence herbicide with glyphosate; (b) postemergence and pre-emergence herbicides with glyphosate, terbuthylazine, diuron and oryzalin; (c) natural flora and (d) tillage to a depth of 10–15 cm. Total Collembola abundance, species diversity and species richness significantly varied between the four practices. Notably, the practice using postemergence and pre-emergence herbicides had significantly lower values. Identification of Collembola at species level allowed an interspecies comparison and revealed significant differences for the most common species between the four practices, with each practice being characterized by a different set of species. None of the species were found to be significantly more abundant in the plots treated with postemergence and pre-emergence herbicides.     

盐渍化灌区土壤水盐时空变异特征分析及地下水埋深对盐分的影响

针对盐渍化灌区土壤盐渍化问题,以河套灌区下游乌拉特灌域为研究区,通过野外实测与室内试验分析结合,采用统计学方法地质统计学原理分析表层土壤(0-20,20-40 cm)及深层土壤(40-100 cm)含水率与盐分(EC值)时空分布和变异规律,以及探求地下水埋深对土壤盐分的影响。结果表明:(1)除6月0-20 cm(9.779%)外,表层土壤含水率变异系数均在12.384%~19.667%,属于中等变异性,深层土壤含水率变异系数较小,在3.513%~9.757%,属于弱变异性;表层土壤盐分(EC值)变异系数在100.845%~129.279%,属于强变异性,深层土壤盐分变异系数均在83.685%~98.853%,属于中等变异性;随着土壤深度的增加,含水率和盐分的变异性都相对减弱。(2)不同时期土壤含水率和盐分在一定范围内具有空间结构特征,均可用高斯模型模拟,各层土壤含水率空间相关度在0.038%~20.408%,各层土壤盐分空间相关度在0.043%~8.374%,均小于25%,说明具有强烈的空间相关性,可以认为主要是受结构性因素的影响,其自相关引起的空间变异性较强。(3)试验区土壤盐分主要集中在北侧盐荒地,由于蒸发强烈,包气带毛细水上升,把深层土壤以及地下水中的可溶性盐类带到土壤表层,致使盐分升高,属于典型的盐分表聚型土壤,需及时防治与治理,同时土壤盐分受地下水埋深的影响较大,随着地下水埋深减小而增大,荒地地下水埋深与土壤盐分满足线性关系,耕地地下水埋深与土壤盐分满足指数关系。荒地0-20 cm土壤盐分含量随地下水埋深变化趋势较大,20-40,40-100 cm土壤盐分含量随地下水埋深变化趋势较小,耕地地下水埋深在1~1.6 m时,土壤盐分含量随着地下水埋深变化趋势较大,当地下水埋深大于1.6 m时,土壤盐分含量随着地下水埋深变化趋势较小。研究结果为河套灌区下游盐渍化土壤的防治与改良提供了重要的理论基础和参考依据。     

Spatial variability of soil organic carbon stock in an olive orchard at catchment scale in Southern Spain

Orchards have a high potential for carbon sequestration. However, little research is available on the spatial variability at catchment scale and on the difference between the tree area and the lanes. We analyzed theik spatial variability of soil organic carbon stock, SOC_stock at 90 cm depth in an 8-ha catchment in Southern Spain with olives on a vertic soil. Results showed higher soil organic carbon concentration, SOC, in the tree area as compared to the lane up to 60 cm depth, but its impact on SOC_stock was negligible since it was compensated by the higher soil bulk density in the lane. SOC at different depths was correlated with that in the top 0–5 cm. The overall SOC_stock of the orchard was 4.14 kg m⁻², ranging between 1.8 and 6.0 kg m⁻². This SOC_stock is in the mid-lower range of values reported for olive orchards, measured at smaller scale, and similar to those other intensive field crops and agroforestry under comparable rainfall conditions. The spatial variability in SOC_stock was correlated to several geomorphological variables: elevation, cumulative upstream area, topographic wetness index, sediment transport index, and tillage erosion. Differences in SOC and SOC_stock are driven by the sediment redistribution downslope, mainly by tillage erosion, and higher soil water availability in lower areas allowing higher biomass production. These topographic indexes and the correlation between SOC in the topsoil and SOC_stock up to 90 cm should be further explored in other typology of olive orchards for facilitating the mapping of SOC_stock.     

灌溉对土壤硝态氮淋吸效应影响的研究

在陕北米脂县无定河谷地沙壤质土壤上进行了灌水量对土壤硝态氮的淋失和作物吸收效应影响的研究( 简称淋吸效应) 。结果表明,灌水量在0～4000m3/hm2范围内,与玉米产量和玉米吸N 量之间的关系均呈线性相关。土壤剖面中NO3--N 遗留量主要集中分布在0 ～60cm土层内,出现的高峰在40cm ;在0 ～80cm 土层内的NO3--N 遗留量随灌水量的增加而降低;80 ～320cm 土层内的NO3--N 与灌水量之间无明显相关,320 ～400cm 土层内NO3--N 是随灌水量的增加而增高。不同深度的土壤剖面中NO3--N 遗留量与灌水量之间均呈双曲线相关;氮素损失率以未灌溉和灌水量4000m3/hm2处理的为最低,据此提出了土壤NO3--N 淋吸效应的概念。     

Evaporation and redistribution of salts in a silt loam soil as affected by tillage induced soil mulch

Soil water evaporation, redistribution of surface applied salts and unsaturated hydraulic conductivity were determined in field plots of a silt loam soil kept either untilled or tilled to a depth of 5 cm 2–3 days following irrigation. The hydraulic gradients measured were comparatively steeper and the zone of zero flux during drying occurred at greater depths in untilled than tilled soil. Tillage induced soil mulch reduced evaporation losses; its effectiveness, however, decreased during high external evaporative demand conditions. Some empirical relations to determine evaporation utilizing more easily accesible parameters, such as surface soil water content or suction and U.S. open-pan evaporation, were established for predictive purposes. Due to reduction in upward movement of water, shallow tillage resulted in decrease in upward movement of salts and thus, increased the efficiency of leaching during intermittent ponding. The empirical relationship describing the leaching process showed a net saving of 12.7% in water required to attain 70% removal of surface accumulated salts. Increase in unsaturated hydraulic conductivity of soil due to salinization was also observed.     

Spatial variability of water retention parameters and saturated hydraulic conductivity in a calcareous Inceptisols (Khuzestan province of Iran) under sugarcane cropping

The objective of this study was to quantify inherent spatial variability and spatial cross-correlation of the van Genuchten retention parameters and saturated hydraulic conductivity (K_s) of surface and subsurface layers in a calcareous Inceptisols (Khuzestan province, Iran) under sugarcane cropping. Measurements were performed on 100-cm³ undisturbed soil cores collected at 94 locations along a 30-m-long transect with horizontal sampling distance intervals of 0.3 and 1 m at soil depths of 0–40 and 40–80 cm, respectively. Spatial variability was investigated using conventional statistics and geostatistical techniques. Coefficient of variation (CV) varied from 8.2% (for shape parameter, n at 40–80 cm depth) to 256.7% (for K_s at 0–40 cm depth). The n parameter and saturated water content, θ_s, showed a small-scale spatial heterogeneity with a maximum CV of 11.3% for the first depth and 9.2% for the second depth. Most of the hydraulic parameters at both depths showed a spatial structure and convex experimental semivariograms with dominant spherical models with the influence range of 3.2–41 m. In most cases, the extent of spatial correlation scales of cross-semivariograms for pairs of cross-correlated hydraulic variables was found to be different with reference to those relating to the direct semivariograms of correlated variables.     

Nonuniform leaching of nitrate and other solutes in a furrow‐irrigated,sludge amended field

Abstract

Nitrate leaching losses were estimated using soil core samples from three different locations in a furrow irrigated, N fertilized and sludge amended cotton field. These losses were controlled by irrigation efficiency, as well as sources and quantities of N applied. Statistical comparisons of sample locations and N treatments revealed N treatment to be less significant than the field sampling location. However, sludge amended soils had significantly higher levels of nitrates in the root zone and consequently suffered higher nitrate leaching losses. A NO₃‐N profile (30–210 cm) balance indicated that about forty percent (40%) of available NO₃‐N was leached below the root zone (0–150 cm) in the upper two‐thirds of the field plots during the pre‐plant irrigation. Whereas, the lower one‐third of the field did not experience significant nitrate losses below the root zone. A one‐dimensional finite difference layered model, was used to estimate the depth of moisture penetration at the field (furrow) locations following pre‐plant irritation. It was concluded that the lower one‐third of the plots received less than 50% of mean plot application (30 cm) water during pre‐plant irrigation.     

黑龙港流域微地貌与地下水埋深对土壤潜在盐渍化的影响

[目的]对近年河北省曲周县土壤潜在盐渍化进行多方位评价,为预防土壤盐渍化提供科学依据。[方法]通过微咸水灌溉试验、土壤剖面观测和土样分析,从海拔高度、土层深度、地下水埋深、土壤质地几个方面对黑龙港流域土壤盐分运移以及其对土壤潜在盐渍化的影响进行探讨。[结果]从区域角度分析,降雨和用微咸水灌溉加剧了表层盐分向下层淋洗的可能性,从而使土壤盐分多在40—100cm土层聚集。质地较为黏重的土层阻止了土壤盐分的运移而聚积在该土层之上,为土壤潜在盐渍化创造了条件。土壤盐分含量与海拔高度呈现出很好的相关性,其复相关指数R2=0.76。HCO_3~-的表聚现象比较明显,各土层土壤SO_4~(2-)离子和Ca~(2+)离子与全盐含量之间达到了显著和极显著相关(0.88*~1.00**,0.89*~0.97**),Ca~(2+)离子与SO_4~(2-)离子之间达到了显著和极显著相关(0.86*~0.97**)。[结论]微地貌和土体构型的变化将会影响到土壤盐分的重新分配,进而对土壤潜在盐渍化有重要影响。     

Leaching of imidazolinones in soils under a clearfield system

Herbicides with high mobility can leach to deeper layers of the soil and to contaminate underground aquifers. The potential of herbicide leaching in soil can be monitored by chromatography or bioassay methods. This study evaluated the leaching of imazethapyr, imazapic and its commercial mixture (imazethapyr + imazapic) in three tropical soils via a bioassay method. The herbicides were applied in a polyvinyl chloride column and an 80 mm rainfall was simulated. The bioindicator species sorghum (Sorghum vulgare) BRS 655 was sown. Imazethapyr, imazapic and the commercial herbicide mixture showed high leaching in the soils. The presence of imazethapyr and the commercial mixture was detected up to 25 cm deep in Haplic Plinthosol and Oxisol. Imazapic showed less leaching to tree soil, being found at depth 10–15 cm. The pH, texture and iron oxide amount levels affected herbicide leaching. The mobility of the herbicides imazethapyr and imazapic in the Haplic Plinthosol and the Oxisol at depth 25 cm indicates a high risk of groundwater contamination.     

滨海重度盐碱地微咸水滴灌水盐调控及月季根系生长响应研究

滨海盐碱地是滨海地区重要的土地资源,随着滨海地区城镇化进程及生态文明建设的发展,迫切需要低成本、快速、可持续的滨海盐碱地原土植被构建技术。针对滨海盐碱地原土建植与咸水/微咸水资源的利用,该研究以月季(Rosa chinensis)为例,采用微咸水滴灌技术进行滨海盐碱地水盐调控植被构建。试验在渤海湾曹妃甸区吹沙造田形成的典型沙质滨海盐渍土上进行,设计了灌溉水电导率(ECiw)为0.8、3.1、4.7、6.3、7.8 dS/m的5个处理,研究滴灌水盐调控对土壤盐分淋洗及月季根系生长和分布特征的影响。结果表明:在渤海湾滨海地区气候条件下,先进行淡水滴灌盐分强化淋洗和缓苗灌溉,随后采用7.8 dS/m的微咸水滴灌,0～100 cm土层土壤盐分得到了有效的淋洗,尤其是根层0～40 cm土壤盐分经过一个月左右,由初始28.33 dS/m降低到均小于4 dS/m,一个低盐适生的土壤环境得到快速营造;随着ECiw的增加,0～40 cm土层土壤最终趋于稳定的盐分呈增加趋势,土壤脱盐过程可以被logistic方程描述,脱盐过程可划分为快速脱盐、缓慢脱盐和盐分趋于稳定3个阶段;94%以上的月季根系主要分布在0～20cm的表层土壤中,随着ECiw的增加,根系生物量显著降低,根系受盐分胁迫生理干旱影响向土壤深处生长以扩大水分空间。研究认为,采用短期淡水滴灌盐分强化淋洗和缓苗淡水滴灌、随后进行微咸水滴灌的方法,可以实现土壤盐分的快速淋洗并维持在较低水平,但受盐分对根系生长的影响会作用于植物地上部分生长及植物存活,因此需要结合植物耐盐性及生产目标(产量、景观)确定适宜灌溉水矿化度阈值。     

宁夏引黄灌区稻田氮素浓度变化与迁移特征

过量施氮与不合理灌水是农田面源污染加剧的主要原因。为了寻求较优的水氮管理模式以促进农业生产和减少农田退水对黄河水体的污染, 在宁夏引黄灌区典型稻田中开展了不同水氮条件下稻田氮素迁移转化规律研究。结果表明: 不同水氮条件下稻田田面水NH₄⁺-N 与NO₃^--N 浓度伴随施肥出现明显峰值, NO₃^--N 峰值出现时间较NH₄⁺-N 晚, 且变化较平缓。3 次追肥时期和整个生育期田面水NH₄⁺-N 平均浓度与施氮量和灌水量都呈显著相关, 田面水NO₃^--N 平均浓度与施氮量呈显著正相关, 与灌水量相关性不显著。稻田30 cm与60 cm 深度的直渗水NH₄⁺-N 浓度受施肥影响较大, 与田面水NH₄⁺-N 浓度变化规律相似, 90 cm 处直渗水NH₄⁺-N 浓度峰值出现较为滞后, 且浓度较上层土体低, 120 cm 处直渗水NH₄⁺-N 浓度大体呈现持续上升趋势,整个生育期直渗水NH₄⁺-N 平均浓度与施氮量呈显著相关, 仅30 cm 处NH₄⁺-N 平均浓度与灌水量呈负相关, 其他土层深度不显著。30 cm 与60 cm 直渗水NO₃^--N 浓度在首次灌水后急剧下降, 在施肥后有较小幅度上升, 90 cm 与120 cm 直渗水NO₃^--N 浓度下降缓慢, 仅30 cm 处NO₃^--N 平均浓度与施肥量显著正相关。总的结果表明减少施肥或灌水均可达到减少农田氮素淋失的目的。     

Movement of the protozoan pathogen Cryptosporidium parvum through three contrasting soil types

The potential for transfer of the protozoan pathogen Cryptosporidium parvum through soil to land drains and, subsequently, water courses following the application of livestock waste to land was monitored in the laboratory using simulated rainfall and intact soil cores. Following irrigation over a 21-day period, Cryptosporidium parvum oocysts applied to the surface of soil cores (initial inoculum concentration 1×10⁸ oocysts core^–1) were detected, albeit in low numbers, in the leachates from clay loam and silty loam soils but not in that from a loamy sand soil. Variations in leaching patterns were recorded between replicate cores. At the end of the study soil cores were destructively sampled to establish the location of oocysts remaining within the soil. Distribution within cores was similar in all three soil types. The majority (72.8+-5.2%) of oocysts were found in the top 2 cm of soil, with numbers decreasing with increasing depth to 13.2±2.8%, 8.39±1.4%, and 5.36±1.4% at depths of 10, 20, and 30 cm, respectively.     

灌溉方法对保护地土壤有机氮矿化特性的影响

采用Stanford和Smith提出的长期间歇淋洗通气培养法,对连续7a采用渗灌、滴灌和沟灌灌溉,栽培番茄的保护地不同剖面层次土壤的有机氮矿化特点进行了研究。渗灌管为发汗式半软管,埋深为30cm;渗灌、滴灌和沟灌灌水方法及施肥、田间管理同当地农业生产。当20cm深处的土壤水吸力达到40kPa时开始灌水,渗灌和滴灌每次的灌水量是沟灌灌水量的1/2。试验结果表明,土壤矿化氮含量随着土层深度的增加而降低。从累积矿化氮量—时间曲线变化的趋势看,可将保护地土壤0～50cm剖面分为三个层次,其中渗灌与滴灌处理相似,为0～20cm、20～40cm和40～50cm土层,而沟灌处理则为0～30cm、30～40cm和40～50cm土层。保护地不同层次土壤有机氮的矿化可以用Twopool模型表达。比较不同灌溉处理,在0～10cm土层,易矿化有机氮含量(N1)表现为滴灌>沟灌>渗灌,易矿化有机氮矿化速率(k1)常数也以滴灌处理最大,说明滴灌更有利于表层土壤易矿化有机氮的形成。与渗灌和沟灌相比,长期使用滴灌灌溉有利于改善保护地土壤有机氮的品质。