Evaluation of soil nutrient status in poplar forest soil by soil nutrient systematic approach

A study was conducted to evaluate the soil nutrient status of poplar plantation by Soil Nutrient Systematic Approach (SNSA) in Jianghan Plain, Hubei Province, China. Soil physiochemical properties were analyzed in laboratory through collection soil samples of study site. Ten treatments of application different fertilizers were designed such as CK, optimum treatment (N, P, K, Zn), N(P, K, Zn), P(N, K, Zn), K(N, P, Zn), +Mg(N, P, K, Zn, Mg), Zn (N,P,K), +2P(N, 2P, K, Zn), +2K(N, P, 2K, Zn), and 2N+2P+2K(2N, 2P, 2K, Zn) for field experiment to test the effect on tree height, diameter (DBH) growth, and dry weight of poplar. The results showed that there was no significant difference in tree heights between treatments with different fertilizers, diameter growth of poplar trees in treatments of lack of N and Zn was significantly slower than that of trees in optimum treatment, and dry weight of poplar dropped significantly for treatment of CK as well as treatments without application N and Zn. It is concluded that N and Zn were main limiting factor for poplar growth. Results from laboratory analysis and field experiment were uniform per-fectly, which proved that SNSA was reliable in evaluating soil nutrient status of poplar plantation.

Nutrient Budget and Soil Nutrient Status in Greenhouse System

This paper is based on nutrient budget and its effects on soil nutrient status in typical greenhouse system in China to provide a basis for raising the utilization rate of fertilizers and maintaining the sustainable development of agriculture in the greenhouse.By investigating the management of 18 representative greenhouses in Shouguang,Shandong Province,China,and analyzing both the greenhouse and open field soil samples,the soil nutrient budget and the trend of nutrient accumulation and translocation in soils were thus studied.The results under greenhouse system showed that the average annual inputs of N,P2O5 and K2O were 4 088,3 655 and 3 437 kg ha-1,respectively.The total inputs of N,P2O5 and K2O provided by chemical fertilizers which are the main source of soil nutrient were 63,61 and 66%,respectively.The utilization rates of N,P2O5 and K2O were only 24,8,46% and the input ratio among N,P2O5 and K2O （1：0.9：0.8） was quite different from the uptake ratio （1：0.3：1.4）.It had caused the excess of N,P2O5 and K2O in the soil,and the theoretical surpluses were 3 214,3 401 and 2 322 kg ha-1,respectively,for N,P2O5 and K2O.The level of the organic matter,total nitrogen,nitrate nitrogen,available phosphorus,and available potassium was increased substantially,and their maximum level was observed in the topsoil （0-20 cm） with an average value being 1.4,1.9,21.2,5.4,and 3.7 times higher than that of the open field soil,respectively.The greenhouse soils showed leaching of the nutrients,especially NO3- which would cause a potential risk to the quality of groundwater in the area.It is necessary to apply more organic manure and provide nutrients according to the crop requirements and soil fertility as it could not only produce high crop yield,but also be beneficial to balance the soil nutrient and improve the utilization rate of fertilizers.Further,there would be no significant surplus of nutrients which may leach out of soil to contaminate the environment.

Effects of Different Types of Chinese Fir Stands on Nu－trient Status of Soils

The effects of different types of Chinese fir stand, including those with various composition (pure andmixed), in various cropping systems (first and continuous cropping system) and at different ages, on thenutrient status of soils in the hilly regions of southern Anhui Province were studied by means of ecologicalsequential comparison on the basis of similar climate and soil type. The work was carried out in the XiaoxiForest Farm of Jingxian County and the Caijiaqiao Forest Farm of Jingde County, where the soil is parayellowsoil derived from phyllite and sandstone. The results revealed that with the increase of age, Chinese fir purestand could accumulate organic matter and nitrogen in the soil but it resulted in decreasing of soil PH and baseions (especially Ca￣(2+)) compared to its mixed stand with broad-leaf trees such as Chinese sassafra.s. In orderto improve the soil fertility, it would be better to mix Chinese fir with broad-leaf trees when afforestation.In the management of Chinese fir pure stand, base compounds and phosphates should be added to the soilfor maintaining soil fertility and raising forest productivity.

Differences in Tree Species Diversity and Soil Nutrient Status in a Tropical Sacred Forest Ecosystem on Niyamgiri Hill Range,Eastern Ghats,India

We have quantitatively analyzed the tree species diversity with respect to soil nutrient status in three sites of a sacred forest ecosystem of Niyamgiri hill range, Eastern Ghats, India. Extensive field surveys and sampling were conducted in 3 sites of the hill range： Site 1 Pterocarpus dominated forest （PTF） （19°40＇02.2＇＇ N and 83°21＇23.1＇＇ E）, Site 2 Mangifera dominated forest （MAF） （19°40＇02.8＇＇ N and 83°21＇40.8＇＇ E） and Site 3 Mixed forest （MIF） （19°36＇47.1＂ N and 83°21＇02.7＇＇ E）. A total of 28 families, 42 genera, 46 tree species, and 286 individual trees were recorded on an area of0.6 ha. Tree density varied between 470 and 49o individuals ha and average basal area between 3.16 and l0.04 m2 ha-1. Shannon Index （H＇） ranged from 2.34 to 4.53, Simpson＇s Index ranged from 0.07 to o.09, and equitability Index ranged from 0.7 to 1.34. The number of individuals was highest in the girth at breast height （GBH） class of 50-7o cm. The soil nutrient status of the three forest types was related to tree species diversity. The soil pH value of the three sites reflected the slightly acidic nature of the area. Species diversity was positively correlated with organic carbon and phosphorus and negatively with nitrogen, EC and pH. The results of the current study may be helpful to further develop a conservation planfor tree species in tropical sacred forest ecosystems.

Effects of film mulching regime on soil water status and grain yield of rain-fed winter wheat on the Loess Plateau of China

Shortages and fluctuations in precipitation are influential limiting factors for the sustainable cultivation of rain-fed winter wheat on the Loess Plateau of China. Plastic film mulching is one of the most effective water management practices to improve soil moisture, and may be useful in the Loess Plateau for increasing soil water storage. A field experiment was conducted from July 2010 to June 2012 on the Loess Plateau to investigate the effects of mulching time and rates on soil water storage, evapotranspiration （ET）, water use efficiency （WUE）, and grain yield. Six treatments were conducted： （1） early mulching （starting 30 days after harvest） with whole mulching （EW）; （2） early mulching with half mulching （EH）; （3） early mulching with no mulching （EN）; （4） late mulching （starting 60 days after harvest） with whole mulching （LW）; （5） late mulching with half mulching （LH）; and （6） late mulching with no mulching （LN）. EW increased precipitation storage efficiency during the fallow periods of each season by 18.4 and 17.8%, respectively. EW improved soil water storage from 60 days after harvest to the booting stage and also outperformed LN by 13.8 and 20.9% in each growing season. EW also improved spike number per ha by 13.8 and 20.9% and grain yield by 11.7 and 17.4% during both years compared to LN. However, EW decreased WUE compared with LN. The overall results of this study demonstrated that EW could be a productive and efficient practice to improve wheat yield on the Loess Plateau of China.

Forecast and Analysis of Soil Moisture Based on SIMPEL Model

The forecast of soil moisture lays foundation for water management in farmlands. The change of soil moisture is influenced by multiple meteorological fac- tors. It becomes much significant for improvement of agricultural production and ef- fective use of water to explore the rule of water dynamic at small scale, spatially or temporally. In the research, water dynamic in soil horizons at 0-40 cm in winter wheat belts was simulated by SIMPLE model as per water balance principle. Fur- thermore, ETp in fields was computed according to Haude method （DVWK stan- dards）; retained amount of water in fields and wilting coefficient were calculated based on soil parameters with SPAW （Soil-Plant-Air-Water）. The simulated results of SIMPLE model showed that the correlation of measured and simulated water con- tent in soils was 0.95 and relative error averaged lower than 3.1%, suggesting that the model would make a more precise estimation of water content in root zone in the area.

Effects of Green Manure Rape Returned to Field on Rice Yield and Soil Fertility

To determine the fertilization effect of the rapeseed green manure Youfei1, we assessed soil physical and chemical properties and the yield of succeeding crop before and after planting Youfei 1. Compared with basal soil samples and controls,improvements were observed in the soil content of available N, P, K, and organic matter. The content of available K and organic matter increased significantly by17.99% and 25.45%. The soil pH did not change noticeably, but the soil bulk density decreased significantly by 22.55%. After planting Youfei 1, the yield of a succeeding rice crop increased significantly by 6.62% in two years. We conclude that planting Youfei 1 can help maintain and improve soil fertility and significantly increase the yield of succeeding crop.

Effect of potassium on soil conservation and productivity of maize/cowpea based crop rotations in the north-west Indian Himalayas

Plots under conservation tillage may require higher amount of potassium(K) application for augmenting productivity due to its stratification in upper soil layers, thereby reducing K supplying capacity in a medium or long-term period. To test this hypothesis, a field experiment was performed in 2002-2003 and 2006-2007 to study the effect of K and several crop rotations on yield, water productivity, carbon sequestration, grain quality, soil K status and economic benefits derived in maize(Zea mays L)/cowpea(Vigna sinensis L.) based cropping system under minimum tillage(MT). All crops recorded higher grain yield with a higher dose of K(120 kg K2 O ha-1) than recommended K(40 kg K2 O ha-1). The five years' average yield data showed that higher K application(120 kg K2 O ha-1) produced 16.4%(P<0.05)more maize equivalent yield. Cowpea based rotation yielded 14.2%(P<0.05) higher production than maize based rotation. The maximum enhancement was found in cowpea-mustard rotation. Relationship between yield and sustainable indices revealed that only agronomic efficiency of fertilizer input was significantly correlated with yield. Similarly, higherdoses of K application not only increased the water use efficiency(WUE) of all crops, but also reduced runoff and soil loss by 16.5% and 15.8% under maize and 23.3% and 19.7% under cowpea cover, respectively. This study also revealed that on an average 16.5% of left over carbon input contributed to soil organic carbon(SOC). Here, cowpea based rotation with the higher K application increased carbon sequestration in soil. Potassium fertilization also significantly improved the nutritional value of harvested grain by increasing the protein content for maize(by 9.5%) and cowpea(by 10.6%). The oil content in mustard increased by 5.0% and 6.0% after maize and cowpea, respectively. Net return also increased with the application of the higher K than recommended K and the trend was similar to yield. Hence, the present study demonstrated the potential yield and profit gains along with resource conservation in the Indian Himalayas due to annual additions of higher amount of K than the recommended dose. The impact of high K application was maximum in the cowpea-mustard rotation.

Soil Geochemistry Changes Induced by a Foreign Soil Reconstruction Project in Three Gorges Reservoir Region of China

Fertile topsoil was added onto the surface of barren slope land in Three Gorges Reservoir region of China in an anthropogenic process known as the foreign soil reconstruction project. The main goal of this paper was to reveal the influence of anthropogenic activities on pedogenic processes and soil classifications. Chemical weathering indices and comparative analysis were applied to discuss changes in geochemical compositions and weathering features of purplish soils(Cambisols) before and after the project. Results showed that:(1) The foreign soil reconstruction project slightly altered the major element composition of topsoil and improved the soil structure. Although the distributions of major elements in the original topsoil, original subsoil, foreign topsoil and newly constructed topsoil were all similar to that in upper continental crust, newly constructed topsoil was the most similar soil.(2) The chemical index of alteration was more sensitive than the weathering index of Parker at indicating chemical weathering status of purplish soil. The chemical weathering status of newly constructed topsoil was higher than that of the original topsoil and lower than that of foreign topsoil.(3) Anthropogenic activities may provide a promising new thought for the anthropogenic soil classification system. The scope and subgroups of Anthrosols should be extended and strengthened. Or there may be a need to combine Anthrosols and Technosols orders to create a new soil order. The results may be used for optimizing soil mellowing engineering activities and enriching the soil classification system.

吉林省主要耕作土壤中含钾矿物组成及其与不同形态钾的关系

通过化学分析 ,X 射线衍射及镜检法研究了黑土、白浆土、黑钙土等吉林省主要耕作土壤的含钾矿物组成及不同形态钾的含量。结果表明 ,土壤中的含钾矿物以含钾长石和伊利石为主 ,钾长石主要集中在土壤砂粒部分 ,伊利石主要存在于土壤的粘粒部分。土壤的含钾矿物总量约占土壤矿物总量的 1/ 3多些 ,比南方土壤高 ;缓效钾含量丰富 ,供钾潜力大 ;速效钾含量在黑土、黑钙土中较高 ,而在白浆土中稍低。 3种土壤的全钾量与含钾矿物总量、粘粒中伊利石含量与粘粒含钾量、伊利石含量与缓效钾量、细砂中含钾长石含量与细砂中全钾量、缓效性钾与速效性钾之间呈极显著或显著相关。