土地利用方式对黄土丘陵土壤CaCO_3含量及分布的影响

本文以具有典型黄土丘陵特征的砖窑沟流域为例,对该流域梁峁地主要土壤类型上不同土地利用方式下0～200cm层土壤剖面CaCO3含量进行了分析。结果表明:土壤CaCO3含量耕地>林地>荒草地;耕地土壤CaCO3有明显的累积层,累积深度约在20～100cm之间;林地累积层深度约在20～60cm之间;而荒草地无明显累积层。这种现象与一般干旱半干旱地区不同。     

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     

不同开垦年限黑土磷素的形态与数量变化

研究了不同开垦年限黑土磷素的形态、数量的变化,结果表明:开垦后黑土全磷含量无明显规律性变化,但土壤有效磷数量显著上升,在土壤磷的组分上,土壤有机磷数量显著下降,而土壤无机磷明显升高。在土壤无机磷的6个组分中,Fe-P、O-P占比例最大;其次Al-P、Ca10-P;再次Ca2-P、Ca8-P。垦后无机磷6个组分含量都有升高,绝对升高量顺序为Fe-P>Al-P>Ca2-P>O-P>Ca10-P>Ca8-P。上升强度顺序为Ca2-P>Al-P>Ca8-P>Ca10-P、Fe-P>O-P.     

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.     

长江三角洲典型地区土壤性质对土地利用变化的响应—以江苏省锡山市为例

以锡山市为分析样区,对土壤pH、有机质、全氮、全磷、速效氮、速效磷和速效钾等7个指标对旱地变为未利用地、水田变为菜地、水田变为旱地、水田变为林地和水田变为未利用地等五种变化方式的响应进行了研究.结果表明,土地利用变化对土壤性质有显著影响,但不同变化方式对各指标的影响方向及影响程度不同：（1）水田变为菜地、旱地和林地使土壤向酸化方向发展,土壤pH分别降低0.47、0.78和0.17;旱地和水田变为未利用地分别使土壤pH提高0.24和0.74;（2）水田变为未利用地、菜地和林地分别使有机质降低3.83、3.18和0.35 g kg^-1;水田变为旱地、旱地变为未利用地分别使有机质含量增加7.58和1.07 g kg^-1;（3）旱地变为未利用地、水田变为菜地和未利用地分别使全氮降低0.31、0.08和0.11 g kg^-1;水田变为旱地和林地分别使全氮提高0.41和0.04 g kg^-1;（4）旱地变为未利用地使全磷有微小幅度的降低,降低量为0.01 g kg^-1;水田变为菜地、旱地、林地和未利用地后不同程度地提高全磷含量,增加量分别为0.23、0.08、0.23和0.09 g kg-1;（5）旱地和水田变为未利用地分别使速效氮降低2.38和7.62 mg kg^-1;水田变为菜地、旱地和林地分别使速效氮增加11.61、34.51和18.26 mg kg^-1;（6）旱地变为未利用地使速效磷降低3.70 mg kg^-1;水田变为菜地、旱地、林地和未利用地分别使速效磷增加45.16、7.54、40.55和10.94 mg kg^-1 ;（7）旱地变为未利用地以及水田变为菜地、旱地、林地和未利用地均使速效钾含量有所增加,增加量分别为8.75、77.44、32.28、160.4和27.59 mg kg^-1.