坡地赤红壤不同利用模式对土壤磷和酶的影响

试验采用广东东莞花岗岩发育的坡地赤红壤为样品进行研究表明 :在坡地赤红壤的 4种利用模式中 ,旱地种植花生 ,荔枝可以有效地改善土壤的酸性 ,提高土壤肥力 ;提高土壤Al-P和Fe -P的含量 ,减少O -P的所占的比例 ,提高坡地赤红壤磷酸盐的有效性 ;增加土壤表层的脲酶和蛋白酶的活性 ,可能使土壤的磷酸酶的活性降低     

Soil nutrient changes due to land use changes in Northern China: a case study in Zunhua County, Hebei Province

Abstract. Since the 1980s, land use in rural areas of China has changed greatly as the result of political initiatives. These changes have caused soil nutrient changes which are examined in this paper for Zunhua County, northern China from 1980 to 1999. The areas of farmland, grassland, and paddy decreased greatly and were replaced by increases in forest and residential land. The soils under forest in 1999 transformed from farmland in 1980 increased in organic matter by 21%, total nitrogen by 18%, available nitrogen by 65%, available phosphorus by 17% and available potassium by 17%. Similarly, in the area which was converted from farmland in 1980 to grassland in 1999, soil organic matter, total nitrogen, available nitrogen, available phosphorus, and available potassium increased by 38%, 37%, 71%, 2% and 28%, respectively. Changes from farmland to forest and grassland not only changed land cover but also improved soil fertility and probably reduced soil nutrient losses.     

贵州中部岩溶丘陵区不同土地利用和管理方式对土壤肥力的影响

本文研究了黔中岩溶丘陵区几种不同士地利用和管理方式下土壤物理、化学和生物学性状的特征。结果表明,农林(林草)复合利用模式在土壤粒级组成、孔隙分布、持水性能、有机质和N、P养分、酶活性等方面表现出较好的肥力性状特征,有机无机肥配施、精细管理的灌溉农田次之,而粗放管理的旱坡耕地,土壤肥力性状严重恶化,逐步向石漠化景观演变。不同土地利用方式和管理措施显著影响土地肥力变化的程度和方向,调整土地利用结构,实行基本农田精细管理、陡坡耕地退耕还林(革)是保护土地资源,实现区域生态重建和农业可持续发展的根本途径。     

土地污染的一个评价指标:土壤动物

土地质量评价指标体系成为当前的研究热点,而土地污染是影响土地质量的重要因素。为了对土地质量全面客观地进行评价,提出了土壤动物指标可以作为土地污染的一个间接指标。文章认为土壤动物与土地污染之间存在着密切的关系,并表现在土壤动物各个生物组织层次中:在土壤动物体内累积污染物,在个体层次上表现为毒理学影响,在种群和群落层次上表现为生态学影响。通过对比被污染土地中土壤动物各项指数与未污染土地中土壤动物各项指数,综合得出土壤动物指标,并以此指标作为土地污染的替代指标。     

农用地分等中产量比系数求算方法的研究

对现行《农用地分等规程》中产量比系数计算方法进行探讨,寻求产量比系数的最佳求算方法;研究结果表明《规程》中产量比系数的算法使得研究区冬季作物的自然质量等指数偏大,与实际不符;按两套产量比系数计算的结果则不存在这一问题;建议在农用地分等中,种植制度为一年两熟的地区应分冬夏设两个基准作物,分别编制冬季播种作物和夏季播种作物的产量比系数。     

Tillage and land use effects on soil microporosity in Ohio, USA and Kolombangara, Solomon Islands

Micropores are important to soil moisture retention and plant growth. Microporosity and pore size distribution were evaluated using mercury intrusion porosimetery on aggregates from 35-year-old experiments started in 1962 at Wooster (40.5 °N, 82 °W) and South Charleston (39.8 °N, 84 °W) in Ohio, USA and from three land use practices on Kolombangara (8 °S, 157 °E) in Solomon Islands. Tillage treatments in Ohio included: moldboard plowing (MP), chisel plowing (CP), and no-till (NT) with continuous corn. The land use treatments in Kolombangara included: natural forest (NF), traditional farming (TF) and topsoil removal (TR). Pore size measured in aggregates ranged from 0.2 to 100 μm in diameter. Median pore radius was significantly (P < 0.05) larger for NT than for MP and CP treatments at Wooster, but not at South Charleston. Tillage treatments had significant effect on the volume of both storage and residual pores for both sites in Ohio. Volume of storage and residual pores were higher for Wooster than South Charleston soil. At Kolombangara, the NF treatment had significantly larger median and peak pore radii, and microporosity than TF and TR treatments. There was, however, no significant difference among treatments in the volume of pore size distribution. These data support a recommendation for adoption of no-till or conservation tillage in soils of the temperate region, and of minimal disturbance and effective erosion control in soils of the tropics.     

论北京市耕地后备资源的开发可行性

在对北京市后备资源开发可行性标准进行探讨的基础上,分析了北京市后备资源的开发可行性。研究结果表明北京市后备资源开发面临着的资源质量、生态环境和经济可行性的三重制约。通过土地开发来实现北京市占补平衡不是明智之举。需要改变占补平衡“重开发、轻整理”的现状,使耕地保护的重心从以土地开发为主向以改造中低产田和高标准粮田建设为主要内容的土地整理转变。     

土地利用生态系统分析及服务价值估算——以北京市平谷区白各庄村为例

本研究以北京市平谷区白各庄村为例,详细分析了2002年土地利用生态系统的类型和特点,并进行生态系统服务价值核算,包括物质生产、吸收CO2、释放O2、水供给、废物处理和休闲娱乐,其总价值为1706.62万元,与农村经济总收入基本相等,其中吸收CO2的服务价值最大(72.57%),其次为释放O2价值(15.30%),物质生产服务价值仅占总价值的12.77%,水供给和休闲娱乐服务价值很小,而废物处理服务价值为负值。     

The effect of land cover/vegetation on soil water dynamic in the hilly area of the loess plateau,China

Severe soil and water loss has lead to widespread land degradation in China's loess plateau. During the past decades, a great deal of effort was made on vegetation restoration to reduce soil and water loss in the loess plateau. However, due to water shortage the efficiency of vegetation restoration was not as satisfactory as expected. As part of a vegetation restoration project, we conducted research aiming to understand the relationship between vegetation pattern and soil water dynamics. The goal was to find vegetation types appropriate for the loess plateau with scarce water resources. In 1986, fifteen plots of land were planted with five vegetation types: pine woodland, shrubland, sloping cropland, alfalfa and semi-natural grassland. Soil water content, runoff, soil erosion were measured for each plot. Environmental variables, such as rainfall, evaporation and temperature, were recorded simultaneously by an automated meteorological station. The relationship between land cover pattern and soil water dynamic was evaluated by using statistical models. We found that: (1) soil water loss occurred during the growing season, and it reached the maximum in the second half of July; (2) soil water was not fully replenished from rainfall during the rainy season; (3) pine woodland induced the largest water loss to surface runoff, followed by sloping cropland, alfalfa, semi-natural grassland and shrubland; the poor capability of pine woodland for water conservation may be attributed to soil compaction and poor ground coverage under the tree; (4) in most cases, soil water of the five vegetation types was low except for shrubland and semi-natural grassland where it was moderate-high during a few periods. These conditions inhibit sustainable vegetation growth in the semi-arid loess hilly area of the loess plateau, China.