不同稻田冬茬绿肥对土壤养分、酶活性和微生物数量的影响

本研究通过分析上海青浦地区不同稻田冬茬绿肥翻压后的土壤养分性质、酶活性和微生物数量等指标,采用灰色关联度分析,综合筛选出最有利于土壤培肥的、适宜当地种植的稻田冬茬绿肥轮作模式。本试验设置3个稻田冬茬绿肥处理:紫云英处理(ZY)、蚕豆处理(CD)、油菜处理(YC)。结果表明:(1)不同绿肥轮作模式对于土壤pH、土壤全氮和全磷含量影响均未达到显著性水平,CD和ZY处理土壤全钾含量无显著差异,但均显著高于YC处理;土壤有机质含量顺序为CD>YC>ZY;ZY处理土壤有效磷含量比CD和YC分别高出12.60%和28.70%,YC处理则速效氮和有效钾含量均为最高水平。(2)各绿肥处理的过氧化氢酶和纤维素酶活性无显著性差异,CD处理和YC处理下土壤脲酶活性均显著高于ZY处理,CD处理土壤蔗糖酶活性分别比ZY和YC高出22.10%和55.17%。(3)CD处理土壤细菌、真菌和放线菌数量均处于最高水平,均显著高于ZY处理。(4)绿肥产量与土壤有机质含量、土壤脲酶活性、土壤真菌数量和放线菌数量均呈现显著正相关,其中与土壤脲酶活性的相关性较高(P<0.001);水稻产量与土壤有机质含量和土壤放线菌数量存在显著正相关(P<0.01)。(5)采用灰色关联度分析对16个指标进行综合评价,加权关联度顺序为CD>YC>ZY。综合比较,水稻蚕豆轮作是最适宜试验地区的稻田冬茬绿肥轮作模式。

不同种植年限对贺兰山东麓葡萄园土壤养分特性的影响

贺兰山东麓地区具有独特的地理环境和良好生态条件,是中国优质的葡萄酒产区,土壤营养条件与葡萄酒的品质紧密相关。本研究旨在探究贺兰山东麓不同种植年限葡萄园土壤化学性质及养分状况,以期对该地区特色产业结构调整提供依据。通过方差分析和Pearson相关性分析,对树龄小于5 a、5~10 a、超过10 a的3种不同种植年限葡萄园样地土壤进行了评估。结果显示,当种植年限在5~10 a之间时,土壤pH呈现下降趋势;而当种植年限超过10 a时,pH开始上升。在树龄为5~10 a的土壤中,有效磷和速效钾含量表现出明显的波动,但当树龄超过10 a时,这些含量开始恢复。不同深度层土壤中的有机质、碱解氮、全磷和全钾含量受树龄的影响较小,存在一定范围的波动。养分因子之间的相关性分析发现,当种植年限超过10 a后,养分因子之间的相关性显著降低。这些结果表明,随着种植年限的增加,土壤养分因子以及养分因子之间的关系会发生变化,这为优化贺兰山东麓地区葡萄园土壤管理和改良提供了依据。

安徽沿淮地区潮土理化性质及低养分机理研究

利用大量的测试数据,综合分析了安徽沿淮潮土的耕层养分特征;通过四个土属典型剖面的描述和测试,研究了潮土的理化性质:透气性较好、碱性、养分低且随深度递减、有机质与全氮同步变化等。根据土壤中氮循环原理分析了潮土中氮含量低的实质,即有机质及碳源供应不足、潜水位高及水淹潮土促进了反硝化作用、种植结构的影响等。对原状土铵吸附试验成果进行了计算分析,得出沿淮潮土铵吸附容量值。从而揭示了安徽沿淮潮土低养分(低产)机理,为本区及类似条件下其它地区的土壤改良提供了参考。

不同施氮水平玉米种植地施入有机物料对白浆土养分性状的影响

以典型白浆土区玉米“3414”肥效试验下4个施氮水平,分别配施黄腐酸、腐熟羊粪、玉米秸秆粉末和固化秸秆颗粒的耕层土壤为试材,采用田间试验法,研究了玉米不同生育期白浆土速效养分和有机质含量的动态变化规律。结果表明:(1)在4个施氮水平下,相比于拔节期,玉米腊熟期各有机物料的施入均能有效提高白浆土碱解氮含量,而在减量施氮条件下黄腐酸能使碱解氮含量下降5.1%;(2)固化秸秆颗粒在各施氮水平下均能提高白浆土有效磷含量,相反,黄腐酸在各施氮水平下均能降低白浆土有效磷消耗,基于推荐施氮和过量施氮的情况,腐熟羊粪对白浆土有效磷含量的提升效果最佳;(3)固化秸秆颗粒、腐熟羊粪和黄腐酸在各施氮水平下均有助于白浆土速效钾含量提升,玉米秸秆粉末在不施氮或推荐施氮下能使白浆土速效钾含量降低;(4)固化秸秆颗粒在各施氮水平下均可有效提高白浆土有机质含量,玉米秸秆粉末和腐熟羊粪在不施氮、减量施氮和过量施氮条件下均能使白浆土有机质含量增加,相反,黄腐酸在3个施氮水平下均能使有机质含量降低。

松针凋落物与蚯蚓粪好氧腐解的最佳质量比

以长白山红松林松针凋落物和蚯蚓粪为试材,采用室内培养法,研究二者质量比为10∶0(Ⅰ)、9∶1(Ⅱ)、7∶3(Ⅲ)、5∶5(Ⅳ)、3∶7(Ⅴ)、1∶9(Ⅵ)和0∶10(Ⅶ)时好氧腐解90 d期间pH、养分含量、C/N比、T值、可提取腐殖酸E4/E6、腐殖化指数(CHA/CFA)及发芽指数(GI)的动态变化,筛选二者腐解的最佳质量比。结果表明:与0 d相比,经90 d腐解,各处理pH、P2O5、K2O和总养分含量均有所增加,而N含量增减规律不一。腐解结束时,各处理pH均处于7.06~7.94、总养分含量均大于5%,符合NY525-2012有机肥料农业行业标准;腐解前、后,各处理C/N比由24.4%~26.3%降至14.3%~22.8%,凋落物与蚯蚓粪混合腐解的效果要明显优于二者单独腐解的结果。根据C/N比和T值结果,Ⅲ~Ⅴ处理更有利于腐解;腐解完成时,Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅵ处理腐殖酸品质均有所改善,其中Ⅳ处理更易促进CFA向CHA的转化,使腐殖化程度增强,Ⅴ处理经再缩合形成的腐殖酸分子结构仍保持原有复杂程度,而Ⅶ处理不利于腐殖质品质的提升;各处理GI值在腐解完成时均可获得提升,由腐解前的4.3%~49.8%增至86.6%~137.6%,达到对植物无毒性的标准。松针凋落物与蚯蚓粪以5∶5质量比混合,好氧腐解效果最佳。

Effects of Ploughing Astragalus sinicus at Maturity Stage on Rice Yield and Soil Properties of Paddy Field

[Objective] The effects of ploughing Astragalus sinicus at maturity stage as green manure on paddy soil properties were studied to provide references for ad- vancing the green manure production and field sustainable development. [Methods] A three-year field positioning experiment was carried out. In the first year, five differ- ent levels （0, 2.81, 5.61, 8.42, 11.23 t/hm~） of Astragalus sinicus ploughed at matu- rity stage were designed. And in the next two years, the amounts of ploughed As- tragalus sinicus at maturity stage were based on the natural growth amounts of As- tragalus sinicus at maturity stage of the former year in each plot field. The yields of Astragalus sinicus at maturity stage were estimated and ploughed directly before rice transplanting. Rice yield, soil nutrients, biological properties and water-stable aggre- gates of paddy fields were measured as well. [Results] The effective panicles and rice yields increased significantly after ploughing Astragalus sinicus at maturity stage. Meanwhile, the organic acid content in paddy field increased and the activities of soil phosphatases, invertase and catalase were higher. The soil dissolved organic carbon also increased with the increasing application of green manure. However, excess amount of green manure inhibited the soil microbial biomass carbon content. The macro aggregates and micro aggregates gathered to middle aggregates. [Conclusion] As green manure, the use of Astragalus sinicus at maturity stage could improve soil physiochemical and biological properties, improve soil fertility and increase rice yield significantly. But the ploughing amount of Astragalus sinicus at maturity stage before rice transplanting should be less than 8.42 t/hm2 （dry weight.

Slaughter Performance, Muscle Quality and Muscle Nutrients of Twelve-month-old Tibetan Goat

This study aimed to study the germplasm characteristics of Tibetan goat distributed in Sichuan. Three male and three female goats of twelve-month-old Ti-betan goat were selected, and they were slaughtered for analysis of slaughter per-formance, muscle quality and muscle nutrients. The results showed that the pre-slaughter body weights, dressing percentages, meat percentages and carcass meat production rates of male and female Tibetan goats were （14.33±1.53） and （12.50±2.18） kg, （42.11±5.26）% and （43.85±4.51）%, （31.34±3.36）% and （32.84±3.16）%, and （72.34±0.54）% and （72.30±0.78）%, respectively. There were smal differences in car-cass size, carcass segmentation, muscle fiber properties, muscle quality, muscle nu-tritional composition, muscle minerals contents and muscle heavy metals contents between male and female Tibetan goats. A total of 18 kinds of amino acids were detected in the muscle of male and female Tibetan goats. The EAA/TAA ratios and EAA/NEAA ratios of male and female Tibetan goats were （39.18＆#177;0.38）%and （38.70±0.72）%, and （64.31±1.03）% and （63.21±1.92）%, respectively.

A Study on the Meat and Bone Meal or Poultry By-product Meal as Protein Substitutes of Fishmeal in Concentrated Diets for Paralichthys olivaceus

A study was conducted to evaluate the effects of meat and bone meal （MBM） and poultry by-product meal （PBM） as the replacement of fishmeal in the diets on the growth performance, survival and apparent digestibility coefficient （ADC） of Japanese flounder （Paralichthys olivaceus）. The experimental diets included 0%, 20%, 40%, 60% and 80% MBM or PBM replacement of total fishmeal respectively. All diets were iso-nitrogenous and isocaloric. The results showed that there are no significant differences （P 〉0.05） in growth performance among the treatments fed with 0% -60% MBM replacement of fishmeal, while the percent weight gain （WG, % ）, body length gain （BLG, % ） and ADC significantly decrease when fishmeal is replaced by 80% MBM. The result showed also that there are no significant differences （P 〉0.05） in growth performance and ADC among all treatments fed with the diets with 0% -80% replacements of fishmeal with PBM.

Comparative study on active soil organic matter in Chinese fir plantation and native broad-leaved forest in subtropical China

Active soil organic matter (ASOM) has a main effect on biochemical cycles of soil nutrient elements such as N, P and S, and the quality and quantity of ASOM reflect soil primary productivity. The changes of ASOM fractions and soil nutrients in the first rotation site and the second rotation site of Chinese fir plantation and the native broad-leaved forest were investigated and analyzed by soil sampling at the Huitong Experimental Station of Forestry Ecology (at latitude 26°48′N and longitude 109°30′E under a subtropical climate conditions), Chinese Academy of Sciences in March, 2004. The results showed that values of ASOM fractions for the Chinese fir plantations were lower than those for the broad-leaved forest. The contents of easily oxidisable carbon (EOC), microbial biomass carbon (MBC), water soluble carbohydrate (WSC) and water-soluble organic carbon (WSOC) for the first rotation of Chinese fir plantation were 35.9%, 13.7%, 87.8% and 50.9% higher than those for the second rotation of Chinese fir plantation, and were 15.8%, 47.3%, 38.1% and 30.2% separately lower than those for the broad-leaved forest. For the three investigated forest sites, the contents of MBC and WSOC had a larger decrease, followed by WSC, and the change of EOC was least. Moreover, soil physico-chemistry properties such as soil nutrients in Chinese fir plantation were lower than those in broad-leaved forest. It suggested that soil fertility declined after Chinese fir plantation replaced native broad-leaved forest through continuous artificial plantation.

Effects of intercropping systems of trees with soybean on soil physicochemical properties in juvenile plantations

The intercropping system of tree with soybean in juvenile plantations, as a short-term practice, was applied at Lao Shan Experimental Station in Mao＇er Shan Forest of Northeast Forestry University, Harbin, China. The larch （Larix gmelinii）lsoybean （Glycine max.） and ash （Fraxinus mandshurica） intercropping systems were studied in the field to assess the effects of the intercropping on soil physicochemical properties. The results showed that soil physical properties were improved after soybean intercropping with larch and ash in one growing season. The soil bulk density in larch/soybean and ash/soybean systems was 1.112 g·cm^-3 and 1.058 g·cm^ 3, respectively, which was lower than that in the pure larch or ash plantation without intercropping. The total soil porosity also increased after intercropping. The organic matter amount in larch/soybean system was 1.77 times higher than that in the pure larch plantation, and it was 1.09 times higher in ash/soybean system than that in the pure ash plantation. Contents of total nitrogen and hydrolyzable nitrogen in larch/soybean system were 4.2% and 53.0% higher than those in the pure larch stand. Total nitrogen and hydrolyzable nitrogen contents in ash/soybean system were 75.5% and 3.3% higher than those in the pure ash plantation. Total phosphorus content decreased after intercropping, while change of available phosphorus showed an increasing trend. Total potassium and available potassium contents in the larch/soybean system were 0.6% and 17.5% higher than those in the pure larch stand. Total potassium and available potassium contents in the ash/soybean system were 56.4% and 21.8% higher than those in the oure ash plantation.

Effect of Agricultural Land Use Changes on Soil Nutrient Use Efficiency in an Agricultural Area,Beijing,China

Agricultural land use and management practices may affect soil properties,which play a critical role in sustaining crop production.Since the late 1970s,several new agricultural land use types had been introduced in the rural areas of China.The purpose of this study is to evaluate the effect of these land use changes on the soil properties,nu-trient absorption rate,and nutrient use economic efficiency ratio in an agricultural area of Beijing.Specifically,the cropland,the orchard and the vegetable field were examined.Results of this study suggest that land use and farming management practices significantly affect the content of soil organic carbon (SOC),total nitrogen (TN),total phos-phorus (TP),and available phosphorus in the surface layer of 0-25 cm (p<0.05) in the Yanqing Basin,northwestern Beijing.Soil nutrients in each agricultural land use type decrease rapidly with the increasing soil depth.Orchard and vegetable field tend to have higher soil nutrients than the cropland does.However,the soil nutrient-absorption rate (NAR) of the orchard and vegetable field is lower than that of the cropland,even though orchard and vegetable field may provide much higher economic benefit.While increasing SOC,TN,and TP in the orchard and vegetable field by intensive farming may be a valuable option to improve soil quality,potential increase in the risk of nutrient loss,or agricultural non-point source pollution can be a tradeoff if the intensive practices are not managed appropriately.

Effects of Different Soil Nutrient on the Soluble Solids Content of Cherry Tomato

In order to choose main factors of soil nutrient affecting cherry tomato fruit quality, the soil nutrient content and total soluble solids （TSS） content of cherry tomato in different regions of Lingshui County in Hainan Province was determined, with Millennium cherry tomato as material. The results showed that the TSS content in mature cherry tomato fruit was extremely significant positive to available potassium and exchangeable calcium content in soil, with correlation coefficients of 0.587＊＊ and 0.514＊＊, respectively. The TSS content was significant positive to zinc content, with a correlation coefficient of 0.324＊, And the TSS content showed extremely significant negative to copper content with correlation coefficient of-0.613＊＊ and significant negative to sulfur content with a correlation coefficient reaching -0.332＊. In certain range of contents, the quality of cherry tomato fruit in Lingshui County could be improved through increasing the content of available potassium, exchangeable calcium and zinc in soil, as well as control copper and sulfur content.

Effects of Different Cultivation Media and Periods on the Content of Main Active Components of Cordyceps militaris Strain QC04

In this study,Cordyceps militaris strain QC04 was cultivated in oat,rice,and wheat media for different time periods.We studied the effects of different cultivation media and periods on the fruiting body biomass and active components of C.militaris,aiming to provide reference for the production and utilization of C.militaris QC04.The results showed that the dry weight of the fruiting body of C.militaris was the highest in the wheat medium,moderate in the oat medium,and the lowest in the rice medium.The content of cordycepin and adenosine in the fruiting body and residual medium was higher in the oat and rice media than in the rice medium.The content of cordycepin and adenosine in fruiting body and residual medium peaked on day 55.Furthermore,the content of cordycepin in the fruiting body was lower than that in the residual medium,while the content of adenosine showed an opposite trend.The content of cordycepic acid in the rice medium was generally higher than that in the oat and wheat media.As the cultivation period extended,the fruiting body biomass declined and the content of cordycepic acid in the fruiting body increased slightly.

Analysis on Carotenoids Content and Other Quality Traits of 185 Wheat Varieties

In order to provide the reference of improving the nutritional quality traits in carotenoids and screening its resources of wheat varieties, 185 wheat varieties or lines were selected as materials to test the carotenoids content, lipoxygenase activity, whiteness, yellowness and some other quality traits of whole mill in wheat.The results showed that there were highly significant variations in lipoxygenase activity,carotenoids content, whiteness and yellowness among those sample of wheat varieties; carotenoids content was significantly and positively correlated with yellowness.Cluster analysis was performed based on carotenoids content clustered all the varieties or lines into three major groups. Additionally, carotenoids were discussed in the application of nutritional quality improvement in wheat.

Effects of Long-term Site-specific Fertilization on Soil Physical and Chemical Properties and Nutrients in Dry Farmland

In order to investigate the variation in soil physical and chemical properties and nutrients in the mountainous areas in southern Ningxia, and to provide a theoretical basis for fertilization management in local farmland, the soil p H, total salt content,crop root length, root weight, soil organic matter, available nitrogen, total nitrogen, total phosphorous and total potassium in different fertilization treatments were measured from 2010 to 2016. Multiple comparisons of the data were performed using Duncan's new multiple range test. The results indicated that in the 0-20 cm soil layer, soil p H value and total salt content changed in different patterns, and varied greatly from 2010 to 2016(P<0.05). The changes of both root length and root weight of millet over time fitted S-shaped curves. The root length and root weight in the four fertilization treatments(Treatment 2 to Treatment5) increased faster than those in the control(Treatment 1). The soil organic matter content in all the five treatments gradually increased from 2010 to 2016. The content of alkaline hydrolyzable nitrogen in soil rapidly increased in the first two to three years of the experiment, followed by a slow increase or decrease in 2013, and then raised rapidly again from 2014 to 2016.The soil total nitrogen content varied significantly from 2010 to 2016. The total phosphorus content in soil changed in a different pattern from that of total nitrogen content. The seven-year field trails revealed that soil p H, total salt content, root length, root weight and soil nutrient all changed with the increase of fertilizer level, and that long-term fertilization is of significance for maintaining soil fertility, improving soil quality and reducing soil salinization.

Correlation Between CO_2 Efflux and Net Nitrogen Mineralization and Its Response to External C or N Supply in an Alpine Meadow Soil

In nutrient-limited alpine meadows,nitrogen(N) mineralization is prior to soil microbial immobilization;therefore,increased mineral N supply would be most likely immobilized by soil microbes due to nutrient shortage in alpine soils.In addition,low temperature in alpine meadows might be one of the primary factors limiting soil organic matter decomposition and thus N mineralization.A laboratory incubation experiment was performed using an alpine meadow soil from the Tibetan Plateau.Two levels of NH4NO3(N) or glucose(C) were added,with a blank without addition of C or N as the control,before incubation at 5,15,or 25 ℃ for 28 d.CO2 efflux was measured during the 28-d incubation,and the mineral N was measured at the beginning and end of the incubation,in order to test two hypotheses:1) net N mineralization is negatively correlated with CO2 efflux for the control and 2) the external labile N or C supply will shift the negative correlation to positive.The results showed a negative correlation between CO2 efflux and net N immobilization in the control.External inorganic N supply did not change the negative correlation.The external labile C supply shifted the linear correlation from negative to positive under the low C addition level.However,under the high C level,no correlation was found.These suggested that the correlation of CO2 efflux to net N mineralization strongly depend on soil labile C and C:N ratio regardless of temperatures.Further research should focus on the effects of the types and the amount of litter components on interactions of C and N during soil organic matter decomposition.

Soil Characteristics and Nutrients in Different Tea Garden Types in Fujian Province, China

Anxi is the largest producing area of Tie Guanyin tea in China. “The cultural system of Tie Guanyin tea in Anxi” was selected as “Nationaly Important Agricultural Heritage Systems” （China-NIAHS） in 2014. Tea gardens in this region are organic, ecological or non-ecological. After sampling the soil in these three kinds of tea gardens, we compared soil properties and nutrient content at different soil depths using physical and chemical analyses. Our aim was to provide a scientiifc basis for the management of tea plantations. We measured and analyzed soil in two organic, three ecological and one non-ecological tea gardens at depths of 0–10 cm and 10–20 cm in Anxi County. According to Duncan multiple comparisons and t tests, soil nutrients differed between organic and ecological or non-ecological tea gardens at 0–10 cm. Organic matter and total nitrogen differed between organic and non-ecological tea garden soils at 10–20 cm. In organic tea gardens, soil bulk density, porosity, relative water content, soil organic matter, total nitrogen and total phosphorus were advantageous for tea tree growth. In ecological tea gardens, the indicators were appropriate and relatively advantageous for tea tree growth at a soil depth of 0–10 cm. For non-ecological tea garden, the nutrients were at a compact level and negatively affect tea growth. These results show that soil properties and nutrient content in organic and ecological tea gardens are superior to non-ecological tea garden. The development of organic tea gardens is the most suitable strategy for the growth of tea trees.

Clay Addition to Sandy Soil Influence of Clay Type and Size on Nutrient Availability in Sandy Soils Amended with Residues Differing in C/N ratio

Addition of clay-rich subsoil to sandy soil results in heterogeneous soil with clay peds （2-mm） or finely ground （〈 2 mm） clay soil （FG）, which may affect the nutrient availability. The aim of this study was to assess the effect of clay soil particle size （FG or peds） and properties on nutrient availability and organic C binding in sandy soil after addition of residues with low （young kikuyu grass, KG） or high （faba bean, FB） C/N ratio. Two clay soils with high and low smectite percentage, clay and exchangeable Fe and A1 were added to a sandy soil at a rate of 20% （weight/weight） either as FG or peds. Over 45 d, available N and P as well as microbial biomass N and P concentrations and cumulative respiration were greater in soils with residues of KG than FB. For soils with KG residues, clay addition increased available N and initial microbial biomass C and N concentrations, but decreased cumulative respiration and P availability compared to sandy soil without clay. Differences in measured parameters between clay type and size were inconsistent and varied with time except the increase in total organic C in the 〈 53 μm fraction during the experiment, which was greater for soils with FG than with peds. We concluded that the high exchangeable Fe and A1 concentrations in the low-smectite clay soil can compensate a lower clay concentration and proportion of smectite with respect to binding of organic matter and nutrients.

Soil Properties and Wheat Growth and Nutrients as Affected by Compost Amendment Under Saline Water Irrigation

A greenhouse experiment was conducted to test and compare the suitability of saline compost and saline irrigation water for nutrient status amendment of a slightly productive sandy clay loam soil, to study the macronutrient utilization and dry matter production of wheat （Triticum aestivum c.v. Gemmiza 7） grown in a modified soil environment and to determine the effects of compost and saline irrigation water on soil productivity. The sandy clay loam soil was treated with compost of five rates （0, 24, 36, 48, and 60 m3 ha-1, equivalent to 0, 3, 4.5, and 6 g kg-1 soil, respectively） and irrigation water of four salinity levels （0.50 （tap water）, 4.9, 6.3, and 8.7 dS m-l）. The results indicated that at harvest, the electrical conductivity （EC） of the soil was significantly （P 〈 0.05） changed by the compost application as compared to the control. In general, the soil salinity significantly increased with increasing application rates of compost. Soluble salts, K, C1, HCO3, Na, Ca, and Mg, were significantly increased by the compost treatment. Soil sodium adsorption ratio （SAR） was significantly affected by the salinity levels of the irrigation water, and showed a slight response to the compost application. The soil organic carbon content was also significantly （P 〈 0.05） affected by application of compost, with a maximum value of 31.03 g kg-1 recorded at the compost rate of 60 m3 ha-1 and the irrigation water salinity level of 8.7 dS m-1 and a minimum value of 12.05 g kg-1 observed in the control. The compost application produced remarkable increases in wheat shoot dry matter production. The maximum dry matter production （75.11 g pot-1） occurred with 60 ma ha-1 compost and normal irrigation water, with a minimum of 19.83 g pot-1 with no addition of compost and irrigation water at a salinity level of 8.70 dS m-1. Significant increases in wheat shoot contents of K, N, P, Na, and C1 were observed with addition of compost. The relatively high shoot N values may be attributed to increases in N availability in the tested soil caused by the compost application. Similarly, significant increases in the shoot contents of Na and C1 may be ascribed to the increase in soil soluble K and Cl. The increases in shoot P, N, and K contributed to the growth stimulation since P supplied by the compost was probably responsible in saline and alkaline soils where P solubility was very low.

Scale Dependence of Soil Spatial Variation in a Temperate Desert

Spatial variation is a ubiquitous feature of natural ecosystems, especially in arid regions, and is often present at various scales in these regions. To determine the scale dependence of the heterogeneity of soil chemical properties and the dominant scales(factors) for soil heterogeneity in arid regions, the spatial variability of soil resources was investigated in the Gurbantunggut Desert of Central Asia at the scales of 10-3, 10-2, 10-1, 100, 101, 102, 103and 104m(from individual plant to population or community to ecosystem). Soil chemical properties including pH, electrical conductivity(EC), organic carbon, total nitrogen, available nitrogen, total phosphorus, and available phosphorus were considered in the investigation. At a scale of 10-1m, which represented the scale of individual plant, significant enrichment of soil resources occurred under shrub canopy and "fertile islands" formed in the desert ecosystem. Soil EC exhibited the largest heterogeneity at this scale, indicating that individual plants exerted a great influence on soil salinity/alkalinity. Soil nutrients exhibited the greatest heterogeneity at a scale of 102m, which represented the scale of sand dune/interdune lowlands(between communities). The main important factors contributing to soil spatial heterogeneity in the Gurbantunggut Desert were individual plants and different topographic characteristics, namely, the appearance of vegetation, especially shrubs or small trees, and existing sand dunes. Soil salinity/alkalinity and soil nutrient status behaved differently in spatial heterogeneity, with an inverse distribution between them at the individual scale.