EFFECTS OF CRUSHED MAIZE STRAW RESIDUES ON SOIL BIOLOGICAL PROPERTIES AND SOIL RESTORATION

Agriculture soils in the Mediterranean need restoration and rehabilitation after 10 millenia of use and abuse. Maize straw residues crushed at three sizes [<1 (C1), 1–10 (C2) and >10 cm (C3)] at 5 Mg ha⁻¹ y⁻¹ and with and without urea (150 kg N ha⁻¹) were applied during a period of 3 years for the purpose of restoration of a Typic Xerofluvent located near Córdoba (Spain). The effect on the vegetal cover and biological properties (microbial biomass, soil respiration and enzymatic activities) were determined. The size of the crushed maize residues (particle size <1 cm) and N supply influenced in the evolution of soil biological properties and vegetal cover. The stimulation of microbial biomass, soil respiration, dehydrogenase, urease, β‐glucosidase, phosphatase and arylsulphatase activities was higher in C1 + N‐amended soils for 14·9%, 16·3%, 8·8%, 24·3%, 13·5%, 7·1% and 10·3%, respectively, compared with C2 + N and for 25·8%, 26·9%, 18·3%, 38·5%, 28·2%, 19·1% and 18·3%, respectively, compared with C3 + N. Vegetal cover from the C1 + N treatment was 11·4%, 17·8%, 29·4%, 37·6%, 44·9% and 75·1% greater than that in C2 + N, C3 + N, C1, C2, C3 and control soil. These results suggested that under dry climatic conditions, the application of crushed maize straw finely crushed + N fertilizers improved the soil biological properties and also favour the appearance of spontaneous vegetation, which will protect the soil and will contribute to its restoration. Consequently, the addition of the crushed maize straw finely crushed + N fertilizers may be considered a good environmental strategy for recovery of degraded soils. Copyright © 2014 John Wiley & Sons, Ltd.     

红壤地区杉木人工林土壤肥力质量性状的演变

通过在江西省红壤地区主要林区的铜鼓县和德兴县选择不同林龄（1～28年）的杉木人工林样地采用随机网格法对土壤分层取样，并对土壤样品进行分析后的研究结果表明，从造林阶段到5～8年的幼林期，包括林地凋落物层、土层厚度、有机质、全N、CEC、BS、pH和速效N、P、K在内的林地主要土壤质量性状大幅度退化。随着树龄的增大，林地土壤质量性状开始缓慢恢复。但是，即使杉木人工林进入了主伐期，土壤质量性状的恢复程度仍选低于其初始水平。     

设施土壤次生盐渍化及其对土壤性质的影响

设施土壤次生盐渍化是我国设施农业生产中的一个重要限制因子。本文根据近年来的相关研究进展,综述了设施土壤次生盐渍化的基本特征、形成原因及其影响因素,并阐述了设施土壤次生盐渍化对土壤理化性质以及土壤微生物状况的影响。     

SOIL QUALITY AND SPATIAL VARIABILITY ASSESSMENT OF LAND USE EFFECTS IN A TYPIC HAPLUSTOLL

Soil management practices can have negative or positive effects on soil quality. Our objective was to assess the effect of long‐term agricultural practices by evaluating selected soil physical and chemical properties. Soil samples were collected from two depths (0 to 15 and 15 to 30 cm) within a native pasture and an adjacent agricultural field that was being used for three different crop rotations. Soil quality was quantified using aggregate stability, bulk density, soil texture and available water content as physical properties and pH, electrical conductivity, organic matter and available phosphorus as chemical properties. The farmland soils were functioning at 71 and 70 per cent of their full potential at the 0‐ to 15‐ and 15 to 30‐cm‐depth increments, respectively, whereas those from the pasture were functioning at 73 and 69 per cent, respectively. The assessment showed substantial loss in soil organic carbon following 50 years of farmland cultivation. Tillage and fertilizer applications were presumably the primary reasons for weaker spatial dependence within farmland at the 0‐ to 15‐cm depth. Grazing was postulated as the main reason for weaker spatial dependence within the pasture soils at the 15‐ to 30‐cm depth. Overall, we conclude that 50 years of cultivation has not caused soil quality to decline to a point that threatens sustainability of the agricultural fields. Copyright © 2011 John Wiley & Sons, Ltd.     

EFFECTS OF CONVERTING FOREST TO AVOCADO ORCHARDS ON TOPSOIL PROPERTIES IN THE TRANS‐MEXICAN VOLCANIC SYSTEM,MEXICO

In the present work, land cover and land use changes between 2003 and 2008 were assessed in the Cupatitzio River sub‐basin located in the Trans‐Mexican Volcanic System and Balsas Depression in Mexico. The effects of land cover conversion from temperate forest to avocado orchards on soil properties were determined. Land cover and land use databases were built for the years 1975, 2003, and 2008 using available cartographic information and interpretation of panchromatic SPOT images for the year 2008. Additionally, soil sampling was carried out in 16 representative sites in the higher parts of the sub‐basin, where avocado plantation dynamics have caused important changes in areas covered by temperate forests. Results show that (i) temperate coniferous and tropical low deciduous forests were reduced at an annual rate of 0·9 per cent (1, 001 ha y⁻¹) between 1975 and 2008; (ii) cropland areas expanded at an annual rate of 0·7 per cent between 1975 and 2008, representing a growth of 553 ha y⁻¹; (iii) wet soil aggregate stability, mechanical resistance to penetration and nitrate (N‐NO₃) concentration in the topsoil layer of Andosols were significantly affected by land use conversion to avocado orchards. Other soil properties such as organic matter, interchangeable K, and available P showed degradation tendencies. These results suggest the importance of implementing strategies for mitigating the accelerated process of transformation and degradation of natural resources in the Cupatitzio River sub‐basin. The implementation of programs for deforestation reduction should be a priority in the restoration strategy. Copyright © 2012 John Wiley & Sons, Ltd.     

SOIL ATTRIBUTES AFTER THE CONVERSION FROM FOREST TO PASTURE IN AMAZON

The conversion from forest to grassland is drastically changing soil characteristics in Amazon, leading to land degradation when it is poorly managed. Chemical and physical changes of a Typic Hapludox were evaluated as a function of the conversion (by means of fire) from forest to Brachiaria brizantha cultivation. Samples from the remaining forest were also sampled. Treatments were made to pastures eight (P8), thirteen (P13) and fifteen (P15) years after conversion, and to land under continuous grazing, and to a remaining forest area (control). The forest soil was more acidic than the pasture soils. Soil density and Ca⁺² increased after the conversion, regardless of the period of grazing. Carbon stocks varied from 31·2 t ha⁻¹ in the forest soil to 37·4 (P8), 33·5 (P13) and 30·7 t ha⁻¹ (P15). Copyright © 2011 John Wiley & Sons, Ltd.     

菌渣还田对梨园土壤性状及梨果品质的影响

在7年生梨树行间进行10、12.5和15kg/m23种投料量的覆土栽培平菇试验,将出菇后的菌渣还田,以探明菌渣还田对梨园土壤性状及梨果实品质的影响。结果表明:(1)与对照相比,菌渣还田使0～40cm土层土壤容重降低7.3%～14.9%(P<0.05),土壤空隙度增加4.2%～11.5%(P<0.05),土壤总有机碳含量提高32.7%～56.0%(P<0.01),活性有机碳含量提高39.2%～92.5%(P<0.01),并提高了活性有机碳占总有机碳含量比例;(2)与对照相比,0～40cm土层细菌数量提高12.1%～47.0%,放线菌数量提高19.5%～82.8%;真菌数量68.7%～163.6%(P<0.01),微生物生物量碳氮分别提高13.4%～32.2%(P<0.01)和9.3%～37.1%;(3)土壤脲酶活性提高23.2%～47.6%(P<0.05),蔗糖酶活性提高25.7%～58.6%(P<0.01),磷酸酶活性提高14.8%～33.6%(P<0.01)、过氧化氢酶活性提高4.8%～20.2%,且随菌渣还田量的增加而增加;(4)菌渣还田使梨单果重提高9.2%～15.0%(P<0.05),硬度增加3.9%～5.3%(P<0.05),可溶性固形物含量提高11.7%～19.5%(P<0.05),可溶性糖含量提高4.2%～6.3%(P<0.05),可滴定酸含量降低3.1%～7.7%。在梨树行间按15kg/m2投料量覆土栽培平菇,还田后的菌渣可显著提高梨园0～40cm土层土壤肥力,并改善梨果实品质。     

SULFUR APPLICATION EFFECTS ON SOIL PROPERTIES IN A CALCAREOUS SOIL AND ON SUGARCANE GROWTH AND YIELD

High pH soils limit availability of pH sensitive nutrients including phosphorus (P), even though abundant levels are present. Application of such nutrients to the soil is ineffective because they quickly get tied up in unavailable forms. Elemental sulfur (S) application in a narrow band to lower root zone pH and increase nutrient availability to the crop is a possible economically feasible solution. A four year field study was conducted in which S was applied to sugarcane (Saccharum spp.) at rates up to 1120 kg S ha^?1 each of the 1st three years in a band using different application methods. Sulfur application effects on soil pH were gradual, causing only a slight reduction in the application zone after one year; but was long lasting, resulting in continuing substantial declines in soil pH in an adjacent zone four years after the first S application. Soil available P, sulfate (SO₄)-S, and salinity levels increased with increasing S applied. Sugarcane plant growth, as indicated by leaf area index during the grand growth period responded to moderate S application levels. Sugarcane yields increased linearly in the plant crop, but showed quadratic responses to S applications in the 1st through 3rd ratoon crops. Initial soil available P levels prior to the first treatment application were at the critical level considered adequate for crop requirements, yet growth and yield increases in response to S application suggest that the critical available soil P levels for sugarcane may be higher than previously established. Sulfur application at rates beyond those necessary to produce maximum yields resulted in salinity problems which probably reduced yields. The ‘stool splitter’ application method, which slices the plant stool using a coulter and places the fertilizer directly in the middle of the furrow caused crop damage and stand loss which persisted for the remainder of the sugarcane crops. Based on the results of this study, a single application of elemental S at up to 1120 kg S ha^?1 directly below the seed cane at planting is recommend for sugarcane on a calcareous soil, with no additional applications in later crops.     

草酸/草酸盐对森林暗棕壤的磷释放效应

模拟森林凋落物淋洗液中的草酸/草酸盐浓度范围,设计了不同浓度草酸/草酸盐溶液一次性浸提和多次连续浸提系列实验,其中的草酸(阴离子)载荷量为0~200 mmol kg-1。结果表明,草酸能显著促进暗棕壤A1层(腐殖质层)磷的释放,土壤磷溶出量随草酸溶液浓度升高而线性增加;但对B层土壤磷的释放效应相对较弱,草酸浓度低于5mmol L-1时B层磷的释放不明显。pH 5.16草酸钠溶液比相同浓度的草酸溶液具有更高的解磷效率,在设置二者浓度为0.5~20.0 mmol L-1时,前者的解磷量是后者的1.51~2.98倍,推断草酸盐溶液或凋落物淋洗液中草酸(盐)类物质促进暗棕壤磷释放的主要机理在于草酸阴离子(C2O42-)配位反应。草酸盐对暗棕壤磷的释放效应具有一定累加性,土壤磷释放量主要由草酸阴离子累积载荷量决定,而与其加入方式(多次或一次性)关系不大;当以pH5.16草酸钠溶液加入时,土壤磷释放量Y(mgkg-1)与草酸阴离子累积载荷量X(mmol kg-1)间的回归方程为Y=-0.000 4X2 0.176 6X 0.425 3,R2=0.990 2。仅以凋落物层溶出的草酸(阴离子)量进行估计,由此增加的A1层土壤磷释放量达2.40 kg hm-2a-1,大约相当于中龄林年吸收磷量的1/3~1/5,因此其实际作用是不可忽视的。     

土壤理化性质对铝电极电位的影响

本文系统研究了土壤的某些主要理化性质对铝电极电位的影响。结果表明，土壤水分，土壤松紧度，土壤盐分及土壤ｐＨ对铝电极电位都有明显影响。在土壤饱和水后和饱和水前的一定含水量范围内，则出现一个很大的电位突降。在同一含水量情况下，电位与土壤容重呈明显的线性反相关。土壤盐分浓度的增高能导致电位的负偏。同时在不同土壤中，盐分的作用也各相同。可变电荷土壤盐分的加入对电位的影响比较明显，从土壤ｐＨ的影响可以区分出     

利用方式对高寒牧区土壤有机碳含量及土壤结构性质的影响

在高山草原带选择了围栏草地、一年生人工草地(先围栏草地后开垦种植燕麦草)和多年生人工草地(先围栏草地后开垦种植多年生垂穗披碱草和无芒雀麦)三种利用方式,就人工草地利用方式对土壤有机碳含量和结构性质的影响进行了研究。研究结果表明,在高寒牧区,开垦自然植被分别种植一年生燕麦草20多年和种植多年生禾草7年以后与围栏草地相比较,0-30cm深度土壤有机碳密度分别平均降低了27.7% 和8.5%,土壤结构的稳定性(MWD)分别平均降低了46.9%和42.6%。同时土壤容重和土壤密度显著增加, 土壤孔隙度显著降低。在高寒牧区开垦自然植被建植人工草地情况下,土壤结构性质的恶化与有机碳(质)含量的降低密切相关。     

田林老山常绿落叶阔叶混交林气候及水文效应的研究

运用对比研究方法,于1982～1990年,对田林老山常绿落叶阔叶混交林及草坡地的主要气象和水文要素进行了定位观测研究,并对所得的数据进行了统计回归分析。结果表明,常绿落叶阔叶混交林在减缓气温和地温振幅,提高空气湿度,减少物理蒸发等方面具有极显著的气候生态效应;对大气降雨量具有截留、再分配,消减地表径流,防止土壤冲刷,水源涵养等良好的水文效应。研究结果说明,常绿落叶阔叶混交林在维护山地中海拔生态平衡中具有重要的作用。     

薪炭林水土保持效益的研究

根据试验小区观测资料,本文分析了降雨量,雨强,土壤渗透及植物对水土流失的影响,结果表明:雨强是影响径流强度的主导因子,雨量是决定径流量的关键。建立植被,增强土壤入渗能力是防止水土流失的有效途径。     

两种森林凋落物分解及其土壤效应的研究

本文对田林老山杉木林和常绿落叶阔叶混交林凋落物的分解状况、微生物数量及凋落物分解的土壤效应进行了初步研究。结果表明:经287d 杉木林和常绿落叶阔叶混交林凋落物的失重率地表样分别为23.8%和24.9%,埋置样分别为35.8%和37.2%;C:N 缩小地表样分别为41.0和32.4,埋置样分别为22.4和20.0。凋落物腐解过程中微生物数量明显上升,但冬季显著下降。凋落物腐解刺激相应土层土壤微生物增长,有机质含量和腐殖质 C,N 含量亦有提高。     

不同利用方式和肥力红壤中水稳性团聚体分布及物理性质特征

研究了不同土地利用方式和土壤肥力对红壤水稳性团聚体及土壤物理性质的影响。结果表明,同一肥力水平下不同土地利用方式的土壤中,>0.25 mm水稳性团聚体含量变化趋势相同,均以旱地土壤含量最低,林地土壤最高。不同肥力水平下,林地、果园、水田中>5 mm水稳性团聚体含量变化均为:高肥力>低肥力。说明随土壤肥力的逐渐增高,有机质胶结物质含量增加,有利于形成更多的水稳性大团聚体。土壤团聚体稳定性与>0.25 mm水稳性团聚体含量呈极显著正相关,这表明>0.25 mm水稳性团聚体含量是影响土壤团聚体稳定性的主要因素。不同土地利用方式下的土壤物理性质(土壤容重、土粒密度、土壤孔隙度)存在较大差异,变化规律也不一致。但土壤容重和土壤孔隙度与>0.25 mm水稳性团聚体含量有很好的相关性。     

黄土丘陵区封禁对侵蚀土壤微生物生物量的影响

采用时空互代法,以典型侵蚀环境纸坊沟流域不同封禁年限的狼牙刺群落和杂灌群落为研究对象,选取放牧地和天然次生林为参照,分析了生态恢复过程中土壤微生物生物量、呼吸强度、代谢商及理化性质的演变特征。结果表明,封禁后土壤理化性质明显改善;微生物生物量随封禁年限的延长变化显著,阳坡随封禁年限增加土壤微生物生物量逐渐增加,25 a后微生物生物量碳、氮、磷较封禁前分别增加252%、161%和174%,但显著低于天然侧柏林,仅为其39.0%、41.8%和53.7%;阴坡封禁前10年微生物生物量迅速增加,随后增加幅度减缓,呈波动式缓慢上升趋势;封禁25 a后微生物生物量碳、氮、磷分别增加108%、93%和102%,但明显低于天然杂灌丛群落和辽东栎林,仅为辽东栎林的54.4%、49.1%和40.1%。土壤呼吸强度在封禁5 a后增大明显,且随着年限增加逐渐上升,阳坡25 a时达到最大值,而阴坡15 a时达到最大值,随后开始有所下降,25 a后降至最低点,但仍显著高于放牧地,相同封禁年限的土壤呼吸强度阴坡明显高于阳坡。qCO2随着封禁进程逐渐降低,25 a后达到最低值。相关性分析显示微生物生物量碳、氮、磷、呼吸强度、qCO2与土壤养分和恢复年限相关性密切,达到显著(p<0.05)或极显著水平(p<0.01)。     

EFFECTS OF LAND USE ON SOIL MOISTURE VARIATIONS IN A SEMI‐ARID CATCHMENT: IMPLICATIONS FOR LAND AND AGRICULTURAL WATER MANAGEMENT

Knowledge of the effects of land use on soil moisture variations is necessary to improve land and agricultural water management in the semi‐arid Chinese Loess Plateau. However, previous studies are insufficient to guide management practice in this area and improvement is needed to help with the development of the ‘Grain for Green’ programme. As part of the ‘Grain for Green’ programme, we examined the effects of five land uses (fallow, grassland, cropland, 3‐year and 8‐year jujube orchards) on soil water variations in a small catchment on the Loess Plateau. Soil moisture at 0–160 cm depth was monitored approximately weekly at 47 sites from 17 August to 19 October 2009 and from 4 April to 27 September 2010 using a portable time domain reflectometer. Results indicated that mean soil water profiles in different land uses varied with time, land use induced spatial variations of soil water but exerted negligible influence on soil water temporal patterns, and soil water content was of the greatest spatial variability with moderate means (approximately 20 per cent). Furthermore, the relationship between standard deviation and mean water content was dependent on soil depth, although it was negligibly affected by land use. Profile soil water for five land uses was different in various seasons, precipitation infiltration depth exhibited a positive correlation with precipitation, and the whole profile soil moisture (0–160 cm) was complemented following a 93·5‐mm rainfall event. The findings presented here provide helpful information for land and agricultural water management in this area. Copyright © 2011 John Wiley & Sons, Ltd.     

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.     

LAND USE/LAND COVER CHANGE ANALYSIS AND ITS IMPACT ON SOIL PROPERTIES IN THE NORTHERN PART OF GADARIF REGION,SUDAN

Several decades of intensive dry land farming in the Gadarif region, located in the Eastern part of Sudan, has led to rapid land use/land cover (LULC) changes mainly due to agricultural expansion, government policies and environmental calamities such as drought. In this paper, an attempt has been made to analyse and monitor the LULC changes using multi‐temporal Landsat data for the years 1979, 1989 and 1999 and ASTER data for the year 2009. In addition, efforts were made to discuss the impact of LULC changes on the selected soil properties. For this, a post‐classification comparison technique was used to detect LULC changes from satellite images. Primarily, three main LULC types were selected to investigate the properties of soil, namely, cultivated land, fallow land and woodland. Moreover, soil samples were also collected at two depths of surface soil from ten sample plots for each of the LULC type. For these soil samples, various soil properties such as texture, bulk density, organic matter, soil pH, electrical conductivity, sodium adsorption ratio, phosphorous and potassium were analysed. The results showed that a significant and extensive change of LULC patterns has occurred in the last three decades in the study area. Further, laboratory tests revealed that soil properties were significantly affected by these LULC changes. The change of the physical and chemical properties of the soil may have attributed to the changes in the LULC resulting in land degradation, which in turn has led to a decline in soil productivity. Copyright © 2011 John Wiley & Sons, Ltd.