Fixed Ammonium Content and Maximum Capacity of Ammonium Fixation in Major Types of Tillage Soils in Hunan Province,China

In order to understand the status of fixed ammonium, fixed ammonium content, maximum capacity of ammonium fixation, and their influencing factors in major types of tillage soils of Hunan Province, China, were studied with sampling on fields, and laboratory incubation and determination. The main results are summarized as follows： （1） Content of fixed ammonium in the tested soils varies greatly with soil use pattern and the nature of parent material. For the paddy soils, it ranges from 135.4 ± 57.4 to 412.8±32,4 mg kg^-1, with 304.7±96.7 mg kg^-1 in average; while it ranges from 59.4 to 435.7 mg kg^-1, with 230.1 ± 89.2 mg kg^-1 in average for the upland soils. The soils developed from limnic material and slate had higher fixed ammonium content than the soils developed from granite. The percentage of fixed ammonium to total N in the upland soils is always higher than that in the paddy soils. It ranges from 6.1 ±3.6% to 16.6±4.6%, with 14.0% ±5.1% in average for the paddy soils and it amounted to 5.8±2.0% to 40.1 ± 17.8%, with 23.5 ± 14.2% in average for upland soils. （2） The maximum capacity of ammonium fixation has the same trend with the fixed ammonium content in the tested soils. For all the tested soils, the percentage of recently fixed ammonium to maximum capacity of ammonium fixation is always bellow 20% and it may be due to the fact that the soils have high fertility and high saturation of ammonium-fixing site. （3） The clay content and clay composition in the tested soils are the two important factors influencing their fixed ammonium content and maximum capacity of ammonium fixation. The results showed that hydrous mica is the main 2：1 type clay mineral in 〈 0.02 mm clay of the paddy soils, and its content in 0.02-0.002 mm clay is much higher than that in 〈 0.002 mm clay of the soils. The statistical analysis showed that both the fixed ammonium content and the maximum capacity of ammonium fixation of the paddy soils were positively correlated with the total 2：1 type clay mineral content and hydrous mica content in 〈 0.02 mm clay and 0,02-0.002 mm clay at the significant level of P0.01 or P0.05, respectively, but not correlated with the total 2：1 type clay mineral content and hydrous mica content in 〈0.002 mm clay significantly, It demonstrated that the ammonium-fixing matrix of the tested soils mainly exists in the 0.02-0.002 mm clay. The above-mentioned results showed that fixed ammonium is a major form of N in the tillage soils in Hunan Province, China. It would play an important role in N nutrition of crops, especially for upland crops, and deserve to be further researched.

The Study of a New Manipulator for a Stone Protector of Stony Soil Tillage Implement

This paper studies the motion of novel manipulator that can be used in the structure of stone protectors of soil tillage implements. According to the virtual reality technology-based method the technology of composition of the virtual model of a manipulator and its positions in the working process are described in details. This virtual model is used for composition the video clip, simulating the motion of novel manipulator, which three points are moving along two lines and one curve. The results obtained and the computer program realizing the virtual reality technology-based study of the working process of the virtual manipulators for stone protectors can be used by designers of stone protectors for soil tillage implements.

Independent and Combined Effect of Some Soil Tillage Systems on Nitrogen and Carbon Concentration in Soil Structural Units of Haplic Chernozems

This paper aimed at studying the effect of different types of soil tillage systems on the change of total carbon （C） and nitrogen （N） in the soil structural units of different size after dry structural analysis of soil. The research was carried out in a 6-field rotation system （grain maize-wheat-sunflower-wheat-bean-wheat） at the end of the 2nd rotation. Six out of 24 soil tillage systems were selected; they were applied independently and in combination in the crop rotation. After that, they were compared to the system with constant deep plowing. So a total of seven soil tillage systems were investigated. The selected systems for main soil tillage were the following： plowing （control variant）, disking, cutting, nil tillage （direct sowing）, plowing-disking, plowing-nil tillage, disking-nil tillage. Three depths of 0-10, 10-20 and 20-30 cm were studied, as well as soil structural units were of the following sizes： 〉 10 mm, 10-5, 5-3, 3-1, 1-0.25 mm and 〈 0.25 mm. As a result of systematic implementation of different soil tillage systems, higher N and C concentrations were established by the layers according to constant plowing. Constant disking and its alternation with nil tillage increased the total N concentration with 15.6% and 11.1%, respectively, in comparison with the constant plowing. The same was valid for C concentration in soil, but the highest increase was established in the variants with constant cutting and nil tillage. The exceeding was with 14.0% and 13.2%, in comparison to constant plowing. The redistribution of N and C depending on the structural soil units was most expressed in the 0-10 cm and 10-20 cm layers. The highest amounts of C and N were found in the soil units with size less than 5 mm, mainly in the 〈 0.25 mm fraction. At depth of 20-30 cm, the role of the size of soil structural units for C and N redistribution decreased strongly. The values of C/N ratio were moderate only under the use of constant disking. This index was low under all other soil tillage systems. The correlation of total N with C in soil was high, positive and significant depending on the size of structural soil units and the tillage systems, as average for the investigated factors in this experiment. The minimal tillage and the tillage without turning of soil, used independently and in combination, had the highest contribution to preserving the organic matter in the haplic Chernozems of Dobrudzha region.

Biological Protection against Fungal Diseases of Winter Wheat under Different Soil Tillage Technologies

The effect of biopreparations, homogenized with the seed （seed treatment before sowing as a dressing）, and used as a mixture with mineral fertilizer ANL （ammonium nitrate with limestone）, upon both grain production and the health state of the winter wheat were evaluated during 2006-2009. Besides conventional soil cultivation, reduced tillage with incorporated chopped straw, and direct drilling into untilled soil covered with mulch, were also used. The following biopreparations were applied： Supresivit （Trichoderma harzianum）, Polyversum （Pythium oligandrum）, and Trianum P （a different strain ofTrichoderma harzianum）. Attention was focused on the foliar fungi pathogens Drechslera tritici-repentis, Septoria tritici, and Alternaria triticina, as well as on the soil-borne pathogenic fungi of the genus Fusarium.

Effects of Agricultural Practices on Soil Organic Nitrogen Fractions in an Inceptisol of a Cocoa Plantation

The effect of agricultural practices on soil organic nitrogen （N） fractions in a cocoa plantation has not been much revealed till now. Despite the fact that soil organic N has been long admitted for its importance to maintain soil fertility. Presented field experiment was conducted in Kaliwining Experimental Station, Indonesian Coffee and Cocoa Research Institute （ICCRI）, Jember, East Java, Indonesia, to investigate the effect of cocoa farm management, namely fertilization, weeding and soil tillage on the content of soil organic N fractions. The design of experiment was arranged in a split-split plot with two levels of weeding as main plots, two levels of soil tillage as subplot and three different fertilizer treatments as sub-sub plot. The analysis of soil N including total N and soil organic N fractions, namely, total hydrolized N, ammonium N, amino sugar N and amino acid N, were performed. The result showed that the effect of fertilization treatment was significant to the content of total N, ammonium N, amino sugar N and amino acid N. No-tillage treatment resulted in total N and amino sugar-N content increasing by 8% and 24%, respectively, over tillage treatment. Slashing treatment caused increase of the total N by 3% from herbicide treatment, whilst decrease of ammonium N and amino sugar N by 7% and 24%, respectively.

Changes in SOC and Nutrients under Intensive Tillage in Two Types of Slope Landscapes

The net effect of tillage erosion on soil properties would be associated with the spatial variation in soil constituents,and therefore plays an important role in ecological agriculture.We conducted a consecutive tillage by hoeing 15 times during a period with no rainfall in the two slope landscapes(a linear slope and complex slope) of the Yangtze Three Gorges reservoir areas,to examine the relationship between soil erosion rates and the variations in soil chemical properties and compare the effects of soil redistribution on SOC and nutrients between the linear and complex slopes.After the simulated tillage,notable changes in 137 Cs inventories of the soil occurred in the summit and toeslope positions on the linear slope,while there were significant changes in 137 Cs inventories at convex and concave positions on the complex slope.Soil profile disappeared at the summit slope boundary,with the exposure area of 16.0% and 7.6% of the experimental plot,respectively,for the linear and complex slopes due to no soil replacement.Soil organic C and nutrients were completely depleted with the disappearance of soil profiles at soil eroding zones,whereas a remarkable increase in SOC,total N and available nutrient concentrations of the post-tillage surface soil and a decrease in total nutrient concentrations(P and K) were found at depositional zones on the linear slope.For the complex slope,however,changes in SOC and nutrient concentrations of the post-tillage surface soil exhibited a patterndifferent from that on the linear slope,which showed a remarkable decrease in SOC and total nutrient concentrations but a slight increase in available nutrient concentrations after tillage in the toeslope position.Due to the gradual increase in soil depth from top to bottom of the slope,SOC and nutrient inventories in the soil profiles were significantly correlated with soil redistribution rates on both the linear and complex slopes.Tillage causes remarkable changes of soil chemical properties in the surface soil layer and soil profile,and increases SOC and nutrient inventories for the soil profile downslope in steeply sloping landscapes.

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.

Influence of preceding crop and tillage system on forage yield and quality of selected summer grass and legume forage crops under arid conditions

Among the crop production factors,preceding crop and tillage management affect the sustainable use of soil resources and ultimately crop growth and productivity.This study aimed at investigating the impact of preceding winter crops(grass or legume)and different tillage systems on forage yield,quality and nutritive values of three summer grass(Sudan grass,pearl millet and teosinte)and two legume forage crops(cowpea and guar)under arid conditions.The results exhibited that growing forage crops after legumes(as berseem clover)produced the highest fresh and dry forage yields and quality attributes compared with grasses(as wheat)with the exception of crude fiber content,which was decreased.Moreover,tillage practices showed positive impact on forage yields and quality attributes.The maximum forage yields and quality parameters were recorded under conventional tillage(CT)practice compared with reduced tillage(RT)and no-tillage(NT)systems.Among the evaluated crops,the highest yields of fresh forage,dry forage,crude fiber,crude protein and total digestible nutrient were exhibited by grass forage crops(Sudan grass,pearl millet and teosinte),whereas the highest crude protein content and the digestible energy values were produced by legume forage crops(cowpea and guar).The maximum fresh forage,dry forage,crude fiber,crude protein,total digestible nutrient and digestible crude protein yields were produced by pearl millet followed by Sudan grass under CT and RT after berseem clover.The highest net return was recorded by sowing pearl millet after berseem clover and applying CT followed by RT practices,which could be recommended for the commercial production.Moreover,it could be assumed that the combination of growing grass forage crops after legume crops under CT or RT systems could enhance forage crop yield and quality with an improvement in soil properties for sustainable agriculture with low cost and the highest net income.

Retention of eucalyptus harvest residues reduces soil compaction caused by deep subsoiling

Eucalyptus harvesting,forwarding and soil tillage operations are among the main causes for compaction of forest soils,with potential impacts on productivity.This concern is especially important in areas with soils that are naturally compacted(fragipans and duripans).In these soils,tillage operations include the use of subsoilers that can reach depths of more than one meter and require heavy tractors that exert high pressure on the soil.One of the ways to try to minimize the effect of this compaction is by retaining harvest residues.The objective of this study was to evaluate the impacts of eucalyptus harvesting on soil physical attributes,as well as to determine the potential of different types of residue management to reduce compaction from the soil tillage operation.Two experiments were conducted in the same area with a Yellow Argisol.In the first experiment,compaction caused by mechanized harvesting with harvester+forwarder was evaluated.In the second experiment,different managements of harvest residues were examined as potential modifiers of soil compaction during tillage for new plantings.For this,three managements systems were tested:(1)retention of all harvest residues and litter from the previous rotation(HR+L),(2)retention of litter from the previous rotation(L),and(3)removal of harvest residues and litter from the previous rotation(WR).Before and after harvest,sampling was carried out in the planting rows and inter-rows,and after tillage,samples were collected in the traffic line of the subsoiler-tractor set.In both experiments,undisturbed soil samples were collected from the center of the 0-10,10-20,20-40,40-60,and 60-100 cm layers to determine soil density and total porosity.In each period and site of evaluation,mechanical resistance to penetration up to the 60-cm depth was also determined.The harvesting operation increased soil density at 0-10 and 60-100 cm depths only in the inter-rows.Retention of harvest residues and litter(HR+L)after harvesting avoided increases in soil density and penetration resistance caused by machine traffic during tillage.The results indicate the importance of retaining harvest residues on forest soils for achieving sustainable utilization and for conserving soil quality.

Fenlong Tillage System by the Theory of “Natural Forces” and Possibility of “Fenlong Agriculture” Establishment

"Natural forces" ——core theory of Fenlong technique is explored in this paper. We break through key core technique of farming and agriculture,and invent new method of Fenlong tillage. Broad-spectrum Fenlong tillage technique system based on "full-layer and bottom-layer superdeep tillage without disturbance of soil layer" is established,which provides the possibility for establishing "modern Fenlong agriculture". When applied in 35 kinds of crops in 24 provinces of China,yield could be increased by 10%-50%,and even 1 times. In the transformation of severe saline-alkali land,corn yield could increase by 73. 0%,and Na,Cl and Mg ions in grain decrease by 20. 81%,1. 47%,and 9. 36% respectively. The newly developed "scarification tillage( reclamation) in the bottom area" could cover "bottom tillage" of dryland,paddy field,degraded grassland,perennial sugarcane,forest and fruit land,traditional Chinese medicine land,and ecological reconstruction of desertification land. It is point out that if Fenlong technique is used in 666 666. 67 km2 of farmland,200 000 km2 of saline-alkali land,666 666. 67 km2 of degraded grassland,and fisheries in rivers and offshore waters are used,trillion yuan of Fenlong economy could be formed,and the nationals will walk towards a healthier new era.Fenlong technique involves agriculture,forestry,water,grass,environment and other aspects,and its global promotion could improve eco-environment and change world development pattern.

Impact of Different Tillage Methods on Silty Loam Luvisol Water Content in Sugar Beet(Beta vulgaris L.)Crop

The regulation of water regime in the soil is the most important task in semi-humid climate with not even precipitation distribution conditions. Reduced or minimum tillage may change soil hydrological properties. The objectives of this study were to investigate the possibilities to manage soil water regime during the whole soil tillage system for sugar beet, which are especially sensitive for water deficit or abundance. Five field experiments were carried out at the Experimental Station of the Lithuanian University of Agriculture (Aleksandras Stulginskis University since 2011) (54°52'N, 23°49'E) during 1995-2010. The soil of the experiments was silty loam Luvisol. In this study we highlighted the reduction of primary soil tillage from deep annual soil ploughing to shallow ploughing, deep and shallow cultivation and no till, comparison of soil ploughing and subsoiling, presowing ploughed or unploughed soil tillage with different cultivators—S-tine, complex, rotary and others, soil compressing with Cambridge and spur rollers before and after sugar beet sowing investigations. According to the results of experiments, reduction of primary soil tillage conserved soil water. The highest storage of soil water in spring was observed in non-reversibly tilled or not tilled soil. Subsoiling led higher water infiltration rate, and top layer of subsoiled soil consisted less moisture content than ploughed. Sugar beet seedbed moisture mostly depended on soil tillage intensity and depth. Presowing rotary tilling was the top tillage method in the case of water preservation in ploughed or unploughed soil. Soil compressing with rollers mostly had negative or low influence on light loam Luvisol moisture content. Rolling with Cambridge roller effected on more rapid water transport from deeper to top sugar beet seedbed layers and higher evaporation rate.

Responses of greenhouse gas fluxes to experimental warming in wheat season under conventional tillage and no-tillage fields

Understanding the effects of warming on greenhouse gas（GHG, such as N2O, CH4 and CO2 ）feedbacks to climate change represents the major environmental issue. However, little information is available on how warming effects on GHG fluxes in farmland of North China Plain（NCP）. An infrared warming simulation experiment was used to assess the responses of N2O, CH4 and CO2 to warming in wheat season of 2012–2014 from conventional tillage（CT） and no-tillage（NT） systems. The results showed that warming increased cumulative N2O emission by 7.7% in CT but decreased it by 9.7% in NT fields（p 〈 0.05）. Cumulative CH4 uptake and CO2 emission were increased by 28.7%–51.7% and 6.3%–15.9% in both two tillage systems,respectively（p 〈 0.05）. The stepwise regressions relationship between GHG fluxes and soil temperature and soil moisture indicated that the supply soil moisture due to irrigation and precipitation would enhance the positive warming effects on GHG fluxes in two wheat seasons.However, in 2013, the long-term drought stress due to infrared warming and less precipitation decreased N2O and CO2 emission in warmed treatments. In contrast, warming during this time increased CH4 emission from deep soil depth. Across two years wheat seasons, warming significantly decreased by 30.3% and 63.9% sustained-flux global warming potential（SGWP） of N2O and CH4 expressed as CO2 equivalent in CT and NT fields, respectively. However, increase in soil CO2 emission indicated that future warming projection might provide positive feedback between soil C release and global warming in NCP.

Discrete element method simulation of disc type furrow openers in paddy soil

For granular materials,discrete element modeling is one of the best computer tools to simulate their behavior and interactions.A field experiment was carried out to evaluate the performance of disc furrow openers in paddy soil.Discrete element simulation was done to develop a 3D DEM model for notched,toothed and double disc furrow openers using EDEM software.Hertz Mindlin contact model with bonding was applied for simulation to fulfill the obligations of the soil moisture and bonding between the cohesive particles.Simulated and field experimental data were compared to determine the applicability in the different working conditions.The results of the simulation validated the applicability of the Hertz-Mindlin contact model with bonding to simulate the no till paddy soil using an extremely narrow tillage tool.The calibrated value of normal and shear stiffness was 5×10^(7)N/m,and the calibrated value of bond normal and shear strength was 3×10^(7)Pa.The relative error(-1.7%to 20.6%)for the double disc furrow opener was lower as compared with that notch typed(29.2%to 44.4%)and toothed type(31.5%to 45.9%)furrow openers.

Impacts of different surface features on soil detachment in the subtropical region

Near-surface features have a great influence on runoff and detachment processes by overland flow,but the contributions are still unclear on steep slopes with yellow soil in subtropical humid regions.Field scouring experiments were conducted to investigate how near-surface features affect hydraulic parameters and detachment rate by overland flow.Five treatments and a baseline(disturbed rootless bare cropland)were designed to identify the contributions from stem-leaves,litter,biological soil crusts(BSCs),root systems and non-disturbance,respectively.The results showed that(1)the values of velocity,Reynolds number and Froude number for vegetated slopes were significantly lower than that of baseline,and stem-leaves made a greater contribution(average of 47.30%)to reducing kinetic energy than the other features;(2)the total contribution rate of grassland was 99.38%,and of this total,1.19,1.44,2.49,49.79 and 44.47%reductions were attributed to the stem-leaves,litter,BSCs,root systems and non-disturbance,respectively.Root system and non-disturbance dominated the detachment rate reduction;(3)with increasing flow rate or slope gradient,the total contribution rate remained between 98%and 100%;and(4)for each treatment,the relationship between detachment rate and hydraulic parameters remained constant,and the stream power was the best predictor to detachment rate.The study results are helpful in evaluating the effects of near-surface features on erosion control and providing reference for government decision-makers to choose appropriate soil conservation and management practices.

Proctor cone penetrometer for in-situ soil strength studies in Nigeria

Investigations of in-situ or laboratory soil strength properties,particularly the resistance of soil to penetration,usually referred to as cone index(CI)are often required in soil tillage and traction studies.This helps in the analysis of the interactions of both tillage tools and tractive elements with the soil.However,penetrometer,the instrument used for measuring this important parameter(CI),is not readily available in Nigeria.Following the recommendations in ASAE standards,a functional proctor cone penetrometer for soft soils has been developed and calibrated.The major parts include the handle,made of half-inch galvanized pipe,constructed in such a way that it can be screwed on and off the pressure shaft conveniently,the graduated pressure and penetration shafts made of stainless steel;the spring loaded pressure chamber,and a cone probe.The penetrometer was calibrated by applying known forces on the handle while noting corresponding penetrations and displacements on the graduated pressure shaft.A performance test was carried out on a clayey loam soil to compare the readings obtained from the developed penetrometer and an imported one.The major difference between the two is that while one is very expensive and scarce to come by,the other is produced locally with locally sourced materials and technology.The cost of the imported one is ten times more than that of the local one.The mean CI obtained for twenty-four random samples on the soil surface for the test area at 18 cm depth was found to be 1.4358 MPa for the local,and 1.5096 MPa for the imported.Regression analysis of the two sets of values of CI for the local and the foreign showed a strong correlation(R2=0.779,P<0.05).This implies that the locally produced proctor penetrometer is reliable for measurements of CI at 0-18 cm soil depth for soft soils.