Anthropogenic influences on Zuni agricultural soils

Farmers in the Zuni area of the semiarid American Southwest have successfully cultivated maize and other crops for over three millennia without using artificial fertilizers. Zuni agricultural fields are among the oldest, more or less continuously cultivated areas in the United States. Traditional Zuni agriculture is based on runoff farming, a system whereby runoff and organic‐rich sediment generated in small watersheds are captured and directed onto fields for crop use. We conducted a study to compare soil properties associated with paired and unpaired cultivated, abandoned, and uncultivated fields to evaluate the long‐term effects of cultivation on soil quality. Sampling and analytical methods of this research are especially applicable to geoarchaeological studies of anthropogenic effects on soil fertility and agricultural sustainability in ancient and traditional historical farming systems. Results of the Zuni soil study indicate that cultivation has altered some soil properties, including bulk density, organic carbon, total nitrogen, and C:N ratios in paired fields, but there is no indication that agricultural soils are degraded. This assessment supports the perception of Zuni farmers that long‐term cultivation has not caused a decline in agricultural productivity. © 2005 Wiley Periodicals, Inc.     

Spatial distribution of nitrate and related factors in the High Plains Aquifer,Texas

Utilizing geographic information systems (GIS) and statistics, objectives of this study were to evaluate: (a) the spatial distribution of nitrate concentrations in groundwater, and (b) associations between nitrate concentrations and: proximity to playa lakes, hydraulic conductivity of soil, well depth, and land use in the High Plains Aquifer, Texas. Data were compiled from wells sampled during 2000–2008. Nitrate concentrations in approximately 9% of wells exceeded the maximum contaminant level for drinking water. Concentrations were generally higher beneath urban and agricultural land, under permeable soil, and in shallow wells (especially in the southern part of the study area). However, concentrations were lower near playa lakes. While playas focus recharge to groundwater, denitrification in reducing environments lower nitrate concentrations beneath them. This study identifies areas vulnerable to nitrate contamination that warrant continued monitoring and mitigation efforts.     

Use of satellite data and GIS for assessing the agricultural potentiality of the soils South Farafra Oasis, Western Desert, Egypt

Overpopulation and food security are the main global problems alert decision makers. In developing countries, such problem put extra pressure for horizontal expansion for agricultural development. The rapid sprawl of urbanized areas on the alluvial land of the River Nile and delta to accommodate the population growth has encouraged governmental and private sector for agricultural expansion in the desert. Unless there are reliable information and accurate studies for land and soil suitability, there will be a collapse of such investment. To evaluate the potential suitability of soil for agriculture development in areas of the western desert, satellite images, geographic information, and field survey including soil profiles and artesian water samples with laboratory analysis were integrated to classify the soils according their suitability for specific crop. The main land qualities of the different mapping units and the crop requirement were rated and matched to obtain the current and potential land suitability using Automated Land Evaluation System “ALES”. The study found that the main physiographic units are plateaus, hilland, mountain, and depression floor. But there are three limiting parameters for land suitability which are the lack of nutrient elements, wind erosion vulnerability, and soil texture. The study concluded that the best crops adapted with the soil conditions and could be feasible for economic use are: (1) native vegetation such as agol, sand trees, sammar, halfaa, bawaal, qordaob, bardi, and qortom; (2) filed crops such as onion, garlic, watermelon and wheat; and (3) fruits such as olive and date palms.     

Dynamics of soil organic carbon following land-use change: insights from stable C-isotope analysis in black soil of Northeast China

Intensive soil tillage is a significant factor in soil organic matter decline in cultivated soils. Both cultivation abandonment and foregoing tillage have been encouraged in the past 30 years to reduce greenhouse gas emissions and soil erosion. However, the dynamic processes of soil organic carbon (SOC) in areas of either continuous cultivation or abandonment remain unclear and inconsistent. Our aims were to assess and model the dynamic processes of SOC under continuous tillage and after cultivation abandonment in the black soil of Northeast China. Soil profiles were collected of cultivated or abandoned land with cultivation history of 0–100 years. An isotope mass balance equation was used to calculate the proportion of SOC derived from corn debris (C₄) and from natural vegetation (C₃) to deduce the dynamic process. Approximately 40% of SOC in the natural surface soil (0–10 cm) was eroded in the first 5 years of cultivation, increasing to about 75% within 40 years, before a slow recovery. C₄ above 30 cm soil depth increased by 4.5%–5% or 0.11–0.12 g·kg^?1 on average per year under continuous cultivation, while it decreased by approximately 0.34% annually in the surface soil after cultivation abandonment. The increase in the percentage of C₄ was fitted to a linear equation with given intercepts in the upper 30 cm of soil in cultivated land. A significant relationship between the change of C₄ and time was found only in the surface soil after abandonment of cultivation. These results demonstrate the loss and accumulation of corn-derived SOC in surface black soil of Northeast China under continuous tillage or cultivation abandonment.     

长三角部分地区土壤中22种有机氯农药的分布特征

针对长三角地区长期工业化对农业生态环境构成较大风险,本文利用气相色谱法对该地区不同利用类型土壤中22种有机氯农药进行测定,研究了有机氯农药的残留状况及其在4条土壤垂向剖面中的分布特征。结果表明,不同利用类型表层土壤中有机氯农药残留平均值为工业园区菜地(139.87 ng/g)工业园区荒地(103.1 ng/g)农业区传统菜地(26.27 ng/g)农业区水稻田(2.50 ng/g)。表层土壤中DDTs和HCHs是主要污染物,DDTs含量为0.14~485.73 ng/g(均值44.43 ng/g),HCHs含量为0.69~66.69 ng/g(均值7.73 ng/g),(DDD+DDE)/DDTs值表明该地区近期外源DDTs输入较少。土壤剖面样品分析表明,DDTs和HCHs的含量均随土壤深度增加而迅速降低,这与剖面土壤包气带岩性均以黏土和亚黏土为主,削弱了地表径流对有机氯农药的垂直迁移动力有关。本研究可为控制和改善该地区污染状况提供相关数据。     

Spatio-temporal patterns of agricultural expansion and its effect on watershed degradation: a case from the mountains of Nepal

Expansion of agricultural at the cost of forested land is a common cause of watershed degradation in the mountain zones of developing countries. Many studies have been conducted to demonstrate land use changes in such regions. However, current knowledge regarding the changes, driving forces and implications of such change within the context of watershed development is limited. This study analyses changes in spatial patterns of agricultural land use and their consequences for watershed degradation during the 1976–2000 period along an altitude gradient in a watershed in Nepal, by means of remote sensing, GIS and the universal soil loss equation. Estimated soil loss ranged from 589 to 620 t ha⁻¹ y⁻¹, while areas of extreme hazard severity (>100 t ha⁻¹) increased from 9 to 14.5% from 1990 to 2000. Spatial distribution of soil loss in 2000 was characterized by 88% of total soil losses being from upland agricultural areas. The study determined that without considering other forms of land degradation, only water erosion was responsible for erosion of a substantial area in a short timeframe. Areas under upland cultivation are in an extremely vulnerable state, with these areas potentially no longer cultivable within a period of 6 years. As sustainability of the watershed is dependent on forests, continued depletion of forest resources will result in poor economic returns from agriculture for local people, together with loss of ecosystem services. Thus, in order to achieve the goal of watershed development, remaining forest lands must be kept under strict protection.     

Influences of revegetation mode on soil water dynamic in gully slope of the Chinese Loess hilly–gully region

Gully slope is one of the most active areas of soil erosion in small watershed of the Chinese Loess hilly–gully region. Although its soil erosion has been effectively controlled with the implementation of the “Grain-for-Green Program” in this region, the soil water storage and distribution have been also impacted. In particular, unreasonable revegetation model has aggravated the water shortage, which may in turn threaten the health of ecosystems. However, yet little is known about the effect mechanism of vegetation on soil water in the gully slope. In this study, we examined the relationship between two revegetation modes, including afforestation (i.e. black locust forest) and natural revegetation (i.e. the grassland), and soil water in a depth of 0–120 cm of the gully slope, during the rainy season. The results showed that the effect of the vegetation to the soil water was smaller than that of the precipitation. Furthermore, the response of soil water to the environmental factors was higher in afforestation vegetation due to its lower soil water content, resulting in higher space dependence for soil water, compared to the natural revegetation. The lower soil water content of the black locust forest was mainly caused by its higher recession rate, not its supply. The soil water was deficient for a long time, caused by afforestation, with a shallower formation depth of the dried soil layer and stronger desiccation degree. However, this deficient could not be effectively relieved until in wet year. In comparison with the ridge slope, the effect of vegetation to soil water in gully slope was stronger, with greater water consumption in afforestation vegetation and the higher water storage in natural revegetation. From the aspect of water resources conservation on the water scale, the natural revegetation was the optimal revegetation mode in the gully slope of the loess hilly region.

     

中国西部特殊地貌区地下水开发利用与生态环境功能保护研究

西北内陆流域平原区降水稀少、蒸发强烈,近50 a来各流域下游区天然绿洲面积不断萎缩。以石羊河流域、艾丁湖流域为研究区,针对下游区天然绿洲退变主因与机制问题,基于农田面积、出山地表径流量及灌溉引用水量、地下水开采量和流入下游区地表径流量调查统计、潜水埋深及包气带水理指标原位监测和地下水水位统测,以及植被类型、分布范围、覆盖度和NDVI指数等遥感解译获得的资料,应用流域水循环和水量均衡理论、时间序列分析和地学多元相关分析方法开展研究,得出如下认识:（1）近50 a来,西北内陆流域下游区天然绿洲严重退化的根源是天然水资源匮乏,主因是人口数量不断增加和上、中游区拦用出山地表径流水量大。（2）灌溉耕地不断扩大是下游区天然绿洲面积萎缩的主要驱动因素,每增加1.0 km2灌溉耕地导致石羊河流域下游、艾丁湖流域平原区的天然绿洲面积分别减少1.35~2.07 km2和1.57~3.83 km2;气候越干旱、上游出山年径流水量越少,灌溉引用出山径流水量占当年总径流量的比率越大,流入下游区地表径流水量越少,由此造成下游区天然绿洲面积减少越大。（3）西北内陆流域天然绿洲退化可控,但是由于水资源不足,制约了天然绿洲退化的可控性。在水资源匮乏背景下,现状人口数量驱动的农田用水规模难以继续调减,需要有序促进经济社会用水规模与天然绿洲修复供水规模之间的和谐程度。因此,本研究成果为西北内陆流域水资源合理开发利用和天然绿洲退化修复提供了重要科学依据。     

黄土丘陵区堆积体边坡对上方来水的侵蚀响应

为探明上方来水类型对工程堆积体高陡边坡下部冲刷侵蚀的定量影响,以神府高速公路沿线典型工程堆积体陡坡坡面(36°)为例,设计4种上方来水类型,通过野外放水冲刷试验分析了不同上方来水类型下堆积体坡面的径流侵蚀输沙过程.结果表明:①上方来水类型对堆积体坡面下部的产流影响较小,却干扰了坡面侵蚀产沙过程,造成土壤流失量增加;②径流深、单宽径流侵蚀力和水流功率均可以较好地预测堆积体边坡下部输沙模数的变化;③单宽径流侵蚀功率可以作为表征坡面尺度次径流事件中径流侵蚀力变化的指标.研究结果可为工程堆积体土壤侵蚀强度评价、侵蚀模型建立及新增水土流失防治提供参考.     

不同林草系统对集水区水量平衡的影响研究

应用SWAT99.2模型(Soil and Water Assessment Tool),系统地研究了红壤丘岗集水区4种林草系统(自然草被、阔叶林、混交林和针叶林)的地表径流、根层渗漏、蒸发蒸腾、土壤蓄水量的时空特点,并用实测的地表径流对模型进行校正和验证,月地表径流的Nash-Sutcliffe模拟效率系数达到0.74,模拟值和观测值的决定系数达0.90。结果表明,降水的年内分配不均造成了径流、渗漏、土壤蓄水量月份之间的差异,年际间气象条件(特别是降水)的差异性导致了水量平衡支出项的年际差异,其中径流量和渗漏量受降水的影响最大,蒸发蒸腾量次之,土壤蓄水量的年变化量受降水的影响最小;林地能有效地减少区域的地表径流量,其中以阔叶林和混交林的效果最好;林地入渗性能大于草地;蒸发蒸腾量是林地水量平衡支出中最大的一项,且3种林地的蒸发蒸腾量均大于草地。水量平衡的预测结果显示,土地利用方式是区域短期水量平衡的主要影响因子。     

西南岩溶小流域农业可持续发展优化模式研究

以贵州为代表的西南岩溶地区,农业人口众多,水土资源匹配程度低,人地矛盾突出,农业发展环境先天不足,农业发展缓慢。文章通过野外实地考察并结合相关理论分析认为,水土资源匹配问题并不是限制农业发展的关键,其关键在于现行农业发展模式收益普遍较低,农业生产要素外流,导致农业生产模式缺乏创新。现行传统农业发展模式下农户收益低,且农业生产机会成本高,导致农户对农业投入减少,农业生产要素外流严重。而提高农业生产收益就成为促进农业可持续发展的关键。因此,根据因地制宜突出特色、农户生计与环境保护兼顾和“外驱”与“内生”农业创新模式相结合的农业建设和发展原则,发展以商品化有机生态农业的发展模式、乡村旅游及农业生产复合发展模式和区域标准化农业联合生产模式为代表的,以保障提高农户收益为核心的新农业发展模式,从根本上促进生产要素回流农业生产,是实现农业生产创新和持续发展的根本所在。      

Characteristics of Non—Point Source Pollution in the Watershed of Miyun Reservoir,Beijing,China

Nitrogen and phosphorus are the major nutrients to cause eutrophication to degrade water quality of the Miyun Reservoir,a very important drinking water source of Bijing,China,and they are mainly from non-point sources.The watershed in Miyun County was selected as the study region with a totoal area of 1400km^2.Four typical monitoring catchments and two experimental units were used to monitor the precipitation,runoff,sediment yield and pollutant loading related to various land uses in the meantime.The results show that the total nutrient loss amounts of TN and TP are 898.07t/a,and 40.70t/a,respectively,in which nutrients N and P carried by runoff are 91.3% and 77.3%,respectively.There is relatively heavier soil eroson in the northern mountain area whereas the main nutrient loss occurs near the northeast edge of the reservoir.Different land uses would influence the loss amounts of non-point source pollutants.The amount of nutrient loss from the agricultural land per unit is highest,that from forestry comes next that from grassland is lowest.However,due to the variability of land use areas,agricultural land contributes a lot to TP and forestry lands to TN.     

The effect of naturally acidified irrigation water on agricultural volcanic soils. The case of Asembagus, Java, Indonesia

Acid water from the Banyuputih river (pH  3.5) is used for the irrigation of agricultural land in the Asembagus coastal area (East Java, Indonesia), with harmful consequences for rice yields. The river water has an unusual composition which is caused by seepage from the acidic Kawah Ijen crater lake into the river. This unique irrigation setting allows the study of soil acidification in situ. This paper assesses the effects of volcanogenically contaminated irrigation water on the chemical properties of the agricultural soils.The changes in soil properties were evaluated by comparing samples taken from the topsoil and sub-soil (1–3 m depth) from areas irrigated with acid water and areas irrigated with neutral water. The field survey thus resulted in four soil categories. Bulk soil composition, organic matter content, moisture content and particle size distribution were determined. Reactive phases were quantified with the selective extractions 1 M KCl, 0.1 M Na-pyrophosphate and 0.2 M acid ammonium oxalate (AAO).By comparing the four soil categories it is shown that the use of the naturally polluted irrigation water has had a large influence on the chemical composition of the topsoil. The composition of the soil solution has changed over the entire investigated soil profile. Furthermore the acid irrigation water has strongly modified the composition of the reactive phases, extracted as KCl, pyrophosphate, and AAO extractable elements, and also the bulk soil composition has been significantly modified. Overall this has resulted in the net dissolution of some elements and the net precipitation of others. The changes in the reactive phases and bulk soil composition are only apparent in the topsoil (0–20 cm) but not in the deeper soil.     

Impact of the geomorphology and soil management on the development of waterlogging in closed drainage basins of Egypt and Saudi Arabia

This paper investigates the interplay of the catchment geomorphology, hydrology and soil properties on the development of waterlogging and land degradation within different dry land catchments in Egypt and Saudi Arabia. Multi-temporal remote sensing data of the Landsat Thematic Mapper and Enhanced Thematic Mapper were collected and processed to detect the land cover changes and development of cultivations within the two areas. The Shuttle Radar Topography Mission Digital Elevation Model were hydrologically processed to delineate the catchment morphometrical parameters and to examine the spatial distribution of cultivated fields and their relation to the extracted drainage networks. The fluvial channels of the Farafra Oasis have largely been obliterated by the prevailing aridity and often buried under aeolian deposits. The soil of these areas are mainly lithic with a high calcium carbonate content, thus limiting the downward percolation of excess irrigation water and therefore develop perched water table and seepage through the buried fluvial channels. On the other hand, the cultivations of Tabuk catchment (which has similar geomorphologic setting to the Farafra Oasis) have shown no signs for waterlogging. This situation is could be related to the different soil properties; the spatial distribution of cultivated areas and the adopted irrigation methods via pivots. The inactive alluvial channels, landforms and irrigation methods have to be considered when planning for a new cultivation in dry land catchments to better control waterlogging hazard. The ‘dry-drainage’ concept can be implemented as the drainage and seepage water, which can be conveyed into certain abandoned playas for evaporation.     

陆面水文过程研究综述

在简单介绍陆面过程模式发展的基础上，从裸土蒸发、植被蒸散、土壤水传输、排水和径流等五个方面详细综述了陆面模式研究中对水文过程的参数化。目前陆面参数化方案中仍存在很大的不确定性，其中陆面水文过程参数化的关键问题包括：土壤分层、土层厚度、根带分布；参数的代表性和移植；观测资料；径流的参数化。分析了径流在陆面模式中的重要性，及目前陆面模式中对径流参数化存在的不足，介绍了部分陆面模式对径流的模拟研究，讨论了未来工作的研究重点。     

Nutrient Loss from Various Land－Use Areas in Shixia Small Watershed of Miyun County,Beijing China

In the Shixia small watershed,twenty experimental plots and two monitoring channels,the residential area and livestock areas were used to monitor the flow,runoff and erosion,Nitrogen and phosphorous concentrations associated with various land uses were analyzed at the same time.The results are presented as follows:(1)TP ,TN and COD concentrations of runoff samples in the residential area and livestock arease are nearly 10 times those in other land-use areas.High nutrient loads are associated with village land use,which is due to unsuitable livestock rising.These areas should be treated as the critical areas of non-point source pollution.(2)Different land use influences intensity the loss nutrients,especially slope tillings in agricultural land.The amount of nutrient loss from agricultural land per unit is highest,that from forestry is intermediated and that frompastures is lowest,However,in consideration of the variability of land-use areas,agricultural land contributes the greatest to TP and forestry land to TN.(3)The concentrations of TN and TP in sediments from gangues are highest ,those in forestry land are intermediate,and those in agricultural land are lowest.Nutrient loss from hilly areas in much greater than from mountainous areas.     

Aspects of agricultural land use in Ireland

Ireland's soil regions consist largely of Luvisols, Cambisols, and Gleysols. Approximately 60% of Ireland's land area is subject to varying degrees of soil limitations. Twenty-five percent of the land area comprises wet lowland mineral soils. Ninety percent of Ireland's agricultural area comprises pasture, hay, and silage. Approximately 30% of the agricultural area is devoted to dairying, and 55% to cattle production. is devoted to dairying, and 55% to cattle production. Trends in agricultural land use indicate that tillage declined substantially while livestock showed a substantial increase particularly in the decade 1965–1975. Research concludes that over 2.8 million ha has a capacity to carry at least 100 LU/40 ha (100 acres). Levels of fertilizer use in Ireland are below EEC levels. The highest fertilizer use levels are associated with the eastern and southern areas of Ireland. Tillage crops occupy only 10% of the agricultural area, while they account for 26% of tertilizer and lime use.     

河姆渡文化田螺山遗址古土壤有机质的地球化学特征及其意义

对浙江河姆渡文化田螺山遗址发掘出土的古水稻田沉积有机质开展了详细的有机地球化学分析,从地球化学角度探讨了以田螺山遗址为代表的河姆渡文化稻作农业发展水平以及后期稻田废弃的原因。研究结果揭示,河姆渡文化时期,先民对稻田的开发管理仍处在初级阶段,以原始沼泽型为主。沉积有机质中非挺水水生植物输入指数、平均链长度和藻类输入指数显示,从河姆渡晚期至良渚晚期,田螺山先民耕作区域土壤有机质中藻类等水生生物输入增加,是一个水体逐渐加深的过程,推测生活区周边湖沼环境水体的加深可能是古水稻田废弃的直接原因,甚至有可能是导致整个遗址衰落的直接原因。     

Late prehistoric soil fertility,irrigation management,and agricultural production in northwest coastal Peru

The Pampa de Chaparrí (Pampa) in hyperarid northwest coastal Peru is an ideal area to study late prehispanic agricultural technology and production because irrigation canals and furrowed fields have been preserved since abandonment approximately 500 years ago. We collected 55 samples for soil characterization, fertility, and micromorphic analyses and compared these results to a noncultivated control soil previously sampled in an adjacent valley. Natural soil fertility levels for maize, cotton, and bean production were generally high during late prehispanic cultivation in the Pampa. Maintaining adequate nitrogren levels for production, however, would have required external inputs from livestock manure, guano, or leguminous plants. The management of low soil salinity levels was possible because of rapidly permeable soils and irrigation waters low in salt. Based on available water capacity and climate conditions, the Blaney‐Criddle Equation yields evapotranspiration rates indicating that irrigation frequency was necessary in a range of every 10–16 days during the growing season. © 2004 Wiley Periodicals, Inc.     

Changes in soil physico-chemical and microbiological properties during natural succession on abandoned farmland in the Loess Plateau

The re-establishment of natural species-rich heath lands on abandoned farmland is one of the main measures in soil erosion control in the Loess Plateau of China. So, it is important to understand how the vegetation and soil properties develop after land abandonment. The objective of this study was to determine how physico-chemical properties, microbial biomass, and enzyme activities changed for abandoned farmland with an age sequence of 0, 1, 5, 7, 10, 15, 20, 25, 30, 40 and 50 years in Zhifanggou watershed (8.27 km²), Shaanxi Province, NW China. The results of this study indicate that species succession after land abandonment in the Zhifanggou watershed on the Loess Plateau resulted in a significant improvement in soil chemical and microbiological properties. Soil organic C, total N, available N and K, soil microbial biomass C, N and P, as well as alkaline phosphatase, catalase, saccharase, and cellulase activity increased with time since plantation establishment increased. In contrast, soil bulk density, pH, and polyphenol oxidase activity decreased after farmland abandonment. Urease and α-amylase decreased until 15 years at the early phase of species succession, and then increased. However, there was no significant change in total P and available P during the restoration. Results only implied the tendency that the herbage was developing toward shrub. Although secondary succession plays an important role which improved soil properties after farmland abandonment, the values of these parameters were still much lower than native forest in 50 years. Thus, vegetation recovery after farmland abandonment in a semi-arid environment would be slow and the improvement of soil properties in the Loess Plateau is likely to require a considerably long period of time.