Differentiation of Soil Fauna Populations in Conventional Tillage and No-Tillage Red Soil Ecosystems

In a field experiment, the populations of major soil fauna groups including earthworms, enchytraeids,arthropods and nematodes were examined in conventional tillage (CT) and no-tillage (NT) red soil ecosystems to evaluate their responses to tillage disturbance. Earthworms, macrry and micro-arthropods were stimulated under NT with earthworms showing the highest population increase by four times, while enchytraeids and nematodes favored CT system, predicting certain adaptability of these animals to plow-disturbed soil environment. On the basis of relative response index it was found that soil fauna was more sensitive to tillage than soil resource base (C and N pools) and microflora. The population structure of soil fauna was also affected by tillage treatments. Analysis on nematode trophic groups showed that bacteria-feeding and plant parasitic nematodes were more abundant in CT soil whereas the proportions of fungivores and omnivorepredators increased in NT soil. Possible reasons for the differentiation in both size and structure of the fauna population were discussed and the ecological significance involved in these changes was emphasized.

Effect of experimental warming on soil respiration under conventional tillage and no-tillage farmland in the North China Plain

Understanding the response of soil respiration to global warming in agro-ecosystem is crucial for simulating terrestrial carbon （C） cycle. We conducted an infrared warming experiment under conventional tillage （CT） and no-tillage （NT） farmland for winter wheat and summer maize rotation system in North China Plain （NCP）. Treatments include CT with and without warming （CTW and CTN）, NT with and without warming （NTW and NTN）. The results indicated that warming had no sig- nificant effect on soil moisture in irrigated farmland of NCP （P〉0.05）. The elevated average soil temperature of 1.1-116℃ in crop growing periods could increase annual soil CO2 emission by 10.3% in CT filed （P〉0.05）, but significantly increase it by 12.7% in NT field （P〈0.05）, respectively. The disturbances such as plowing, irrigation and precipitation resulted in the obvious soil CO2 emission peaks, which contributed 36.6-40.8% of annual soil cumulative CO2 emission. Warming would enhance these soil CO2 emission peaks; it might be associated with the warming-induced increase of autotrophic respiration and heterotrophic respiration. Compared with un-warming treatments, dissolved organic carbon （DOC） and soil microbial biomass carbon （MBC） in warming treatments were significantly increased by 11.6-23.4 and 12.9-23.6%, respectively, indicating that the positive responses of DOC and MBC to warming in both of two tillage systems. Our study highlights that climate warming may have positive effects on soil C release in NCP in association with response of labile C substrate to warming.

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.

Microbial Responses of Soil Fertility to Depth of Tillage and Incorporation of Straw in a Haplic Chernozem in Northeast China

Straw is widely incorporated into soil worldwide,but most studies have concentrated on the effects of straw mulching or incorporation with topsoil.To determine the effect of depth of straw incorporation on bacterial and fungal communities,we established a field experiment in a region in Northeast China with Haplic Chernozems using four treatments:conventional tillage(CT,tillage to a depth of 15 cm with no straw incorporation),straw incorporation with conventional tillage(SCT,tillage to a depth of 15 cm),inversion tillage(IT,tillage to a depth of 35 cm)and straw incorporation with inversion tillage(SIT,tillage to a depth of 35 cm).The soils were managed by inversion to a depth of 15 or 35 cm after harvest.The results show that soil organic carbon content was significantly higher and pH and bulk density were significantly lower in the 15–35 cm layer in IT and SIT than CT and SCT.Fungal abundance was higher with straw incorporation,but fungal diversity was lower in the 0–15 cm layer in SCT and SIT than in CT and IT.Path length in the bacterial network was shorter and connectivity was higher in CT+SCT than in IT+SIT,leading to a more complex ecosystem,and the fungal network had opposite patterns.The key taxa in the phylum Actinobacteriota and Ascomycota in the microbial networks changed dramatically at the genus level following inversion tillage with straw amendment,which may increase bacterial network resistance to environmental disturbances and unstable fungal networks,resulting in large changes in the fungal community involved in the decomposition of recalcitrant straw-derived C and the more efficient acquisition of limiting resources.

Limited impacts of occasional tillage on dry aggregate size distribution and soil carbon and nitrogen fractions in semi-arid drylands

Tillage management that minimizes the frequency and intensity of soil disturbance can increase soil carbon(C)and nitrogen(N)sequestration and improve the resilience of dryland cropping systems,yet the impact of occasional disturbance on soil aggregate formation and the soil organic carbon(SOC)storage within aggregates has not been studied well.We evaluated the effect of four tillage management practices on soil dry aggregate size distribution,aggregate-protected C and N,mineral-associated organic matter carbon(MAOM-C),particulate organic matter carbon(POM-C),and corn(Zea mays L.)and sorghum(Sorghum bicolor(L.)Moench)yields in a semi-arid dryland cropping system.Treatments included conventional tillage(CT),strip-tillage(ST),no-tillage(NT),and occasional tillage(OT)management in a corn-sorghum rotation.Soil macro-aggregates were 51-54%greater under ST,NT,and OT,while small and micro-aggregates were greater in CT.Conventional tillage reduced soil aggregate-associated C by 28-31%in macro-aggregates and 47-53%in small aggregates at 26 months(M)sampling compared to ST,NT,and OT.In clay+silt fraction,CT had 14-16%,21-26%,and 36-43%less SOC at 7,14,and 26M samplings,respectively,than ST,NT,and OT.Aggregate associated N was generally similar under ST,NT,and OT,which was greater on average than CT.Soil MOAM-C and POM-C under ST,NT,and OT were generally greater than respective SOC fractions under CT at 19 and 26 M after OT implementation.Corn and sorghum yields were similar among tillage systems in 2020,but greater under ST,NT,and OT than CT in 2021.Our results suggest that while frequent intensive tillage can lower SOC and N storage,a single stubble mulch occasional tillage after several years of NT does not lead to soil C and N losses and soil structural instability in semi-arid drylands.

Phosphorus Dynamics in Two Poultry-Litter Amended Soils of Mississippi Under Three Management Systems

An experiment arranged in a randomized complete block design with three replications was conducted on a Lexington soil (fine-silty,mixed,active,thermic,Ultic Hapludalfs) and a Loring soil (fine-silty,mixed,active,thermic,Oxyaquic Fragiudalfs) in Mississippi from September 1997 to September 2000 on 18 runoff plots under natural rainfall condition to study the phosphorus (P) dynamics in poultry litter amended soils under three management systems combining tillage and planting date treatments to identify effective management practices in southern U.S.A.The management systems in the study were:1) tillage in the fall prior to litter application followed by a delayed planting of fall forages (CT-DP);2) tillage followed by immediate planting of the fall forage with subsequent litter application (CT-IP);and 3) no-till with planting prior to litter application (NT-IP).The results indicated that there was significant increase in soil P after 3 years of poultry litter application for both Lexington and Loring soils (P < 0.05).Based on P budget analysis,the majority of P from poultry litter application (> 90%),was accumulated in both soils.In Loring soil,soluble P mass in the runoff was significantly higher from NT-IP than from CT-DP and CT-IP over the entire study period (P < 0.01).For both soils,there were no significant differences in sediment P mass between management systems.For Loring soil,CT-DP and CT-IP were effective management practices to mitigate negative effects due to poultry litter application.

Influence of Cropping Systems on Soil Properties in Semi-arid Conditions of Setif, Algeria

The effects of two culture systems, conventional and no-till combined the previous crop （lentil and wheat） on soil properties were studied in the experimental site of the station Technical Institute for Field Crops （ITGC） Setif （Algeria） during the crop year 2011/2012. The results indicate that the no-till system affects positively the variables of soil properties and the organic matter has a rate of 2.89% compared to 2.44% in conventional tillage. If the conventional system has an infiltration of moisture relatively higher than that observed for no-till throughout the cycle, the no-tillage is distinguished by a higher storage of moisture at the end of cycle wheat cultivation. The results also indicate that the density （1.44 g/cm）, permeability （22.79 cm/h） and soil compaction （12.51 kg/cm） in no-till were significantly higher compared to conventional tillage 1.35 g/cm, 14.13 cm/h, 7.40 kg/cm, respectively.

Suction Cup Samplers for Estimating Nitrate-Nitrogen in Soil Water in Irrigated Sugarbeet Production

Efforts have increased to measure nitrate losses from farmland under different management practices due to environmental and public concerns over levels of nitrate-nitrogen (NO3-N) in surface and ground waters. This study evaluated the effect of conventional tillage (CT) and strip tillage (ST) practices and three N application rates on NO3-N concentrations in soil water at a 76 cm depth under irrigated sugarbeet (Beta vulgaris L.) in a clay loam soil. Nitrogen rates were applied as dry urea at 120, 150, 180 kg N ha-1 in 2006;130, 160, 190 kg N ha-1 in 2007;and 110, 140, 170 kg N ha-1 in 2008. Soil water volumes were measured weekly during each growing season using three ceramic suction cup samplers per plot placed at a 76 cm depth below the soil surface under each tillage. Results indicated that NO3-N concentrations at the 76 cm depth in the soil profile were not significantly affected by either tillage practice or by N application rate due to soil variability across the field and due to suction cup samplers’ biased estimate of soil water. The three N rates under CT and ST practices maintained NO3-N concentrations below the root zone to levels exceeding the 10 mg L-1 safe drinking water maximum level in all three years. There were large variations in NO3-N concentrations among replicates within each tillage and N rate that were likely caused by variability in soil physical, hydraulic and chemical properties that impacted water movement through the soil profile, N dynamics and leaching below the root zone of sugarbeet. In conclusion, suction cup samplers are point water measurement devices that reveal considerable variability among replicates within each treatment due to the heterogeneity of field soils. Further, these samplers are not recommended in heterogeneous soils with preferential flow characteristics.

Effects of the nitrification inhibitor nitrapyrin and tillage practices on yield-scaled nitrous oxide emission from a maize field in Iran

Nitrification inhibitors can effectively decrease nitrification rates and nitrous oxide(N_(2)O)emission while increasing crop yield under certain conditions.However,there is no information available on the effects of nitrification inhibitors and tillage practices on N_(2)O emissions from maize cropping in Iran.To study how tillage practices and nitrapyrin(a nitrification inhibitor)affect N_(2)O emission,a split factorial experiment using a completely randomized block design with three replications was carried out in Northeast Iran,which has a cold semiarid climate.Two main plots were created with conventional tillage and minimum tillage levels,and two nitrogen(N)fertilizer(urea)management systems(with and without nitrapyrin application)were created as subplots.Tillage level did not have any significant effect on soil ammonium(NH_(4)^(+))and nitrate(NO_(3)^(-))concentrations,cumulative amount and yield-scaled N_(2)O emission,and aboveground biomass of maize,whereas nitrapyrin application showed significant effect.Nitrapyrin application significantly reduced the cumulative amount of N_(2)O emission by 41%and 32%in conventional tillage and minimum tillage practices,respectively.A reduction in soil NO_(3)^(-)concentration by nitrapyrin was also observed.The average yield-scaled N_(2)O emission was 13.6 g N_(2)O-N kg^(-1)N uptake in both tillage systems without nitrapyrin application and was significantly reduced to 7.9 and 8.2 g N_(2)O-N kg^(-1)N uptake upon the application of nitrapyrin in minimum tillage and conventional tillage practices,respectively.Additionally,nitrapyrin application increased maize biomass yield by 4%and 13%in the minimum tillage and conventional tillage systems,respectively.Our results indicate that nitrapyrin has a potential role in reducing N_(2)O emission from agricultural systems where urea fertilizers are broadcasted,which is common in Iran due to the practice of traditional farming.

Impact of Tillage and Fertilizer Application Method on Gas Emissions in a Corn Cropping System

Tillage and fertilization practices used in row crop production are thought to alter greenhouse gas emissions from soil. This study was conducted to determine the impact of fertilizer sources, land management practices, and fertilizer placement methods on greenhouse gas （CO2, CH4, and N2O） emissions. A new prototype implement developed for applying poultry litter in subsurface bands in the soil was used in this study. The field site was located at the Sand Mountain Research and Extension Center in the Appalachian Plateau region of northeast Alabama, USA, on a Hartsells fine sandy loam （fine-loamy, siliceous, subactive, thermic Typic Hapludults）. Measurements of carbon dioxide （CO2）, methane （CH4）, and nitrous oxide （N20） emissions followed GRACEnet （greenhouse gas reduction through agricultural carbon enhancement network） protocols to assess the effects of different tillage （conventional vs. no-tillage） and fertilizer placement （subsurface banding vs. surface application） practices in a corn （Zea mays L.） cropping system. Fertilizer sources were urea-ammonium nitrate （UAN）, ammonium nitrate （AN） and poultry litter （M） applied at a rate of 170 kg ha^（-1） of available N. Banding of fertilizer resulted in the greatest concentration of gaseous loss （CO2 and N2O） compared to surface applications of fertilizer. Fertilizer banding increased CO2 and N2O loss on various sampling days throughout the season with poultry litter banding emitting more gas than UAN banding. Conventional tillage practices also resulted in a higher concentration of CO2 and N2O loss when evaluating tillage by sampling day. Throughout the course of this study, CH4 flux was not affected by tillage, fertilizer source, or fertilizer placement method. These results suggest that poultry litter use and banding practices have the potential to increase greenhouse gas emissions.

Role of Organic Matter and Carbonates in Soil Aggregation Estimated Using Laser Diffractometry

>Aggregation in many soils in semi-arid land is affected by their high carbonate contents.The presence of lithogenic and/or primary carbonates can also inffuence the role of soil organic matter(SOM) in aggregation.The role of carbonates and SOM in aggregation was evaluated by comparing the grain-size distribution in two carbonate-rich soils(15% and 30% carbonates) under conventional tillage after different disaggregating treatments.We also compared the effect of no-tillage and conventional tillage on the role of these two aggregating agents in the soil with 30% of carbonates.Soil samples were treated as four different ways:shaking with water(control),adding hydrochloric acid(HCl) to remove carbonates,adding hydrogen peroxide(H2O2) to remove organic matter,and consecutive removal of carbonates and organic matter(HCl + H2O2),and then analyzed by laser diffraction grain-sizing.The results showed that different contributions of carbonates and SOM to aggregate formation and stability depended not only on their natural proportion,but also on the soil type,as expressed by the major role of carbonates in aggregation in the 15% carbonate-rich soil,with a greater SOC-to-SIC(soil organic C to soil inorganic C) ratio than the 30% carbonate-rich soil.The increased organic matter stocks under no-tillage could moderate the role of carbonates in aggregation in a given soil,which meant that no-tillage could affect the organic and the inorganic C cycles in the soil.In conclusion,the relative role of carbonates and SOM in aggregation could alter the aggregates hierarchy in carbonate-rich soils.

Sulfosulfuron Persistence in Soil Under Different Cultivation Systems of Wheat(Triticum aestivum)

Many sulfonylurea herbicides have been used under a wide variety of agronomic conditions in numerous crops. An understanding of dissipation rate of herbicide is fundamental for predicting the fate of herbicide in soil. In order to study the sulfosulfuron persistence under different cultivation systems of wheat, a four replicated experiment was carried out in the Hashemabad Reaserch Center of Gorgan, Iran in 2010 in a split plot design with two factors. Cultivation system as the main factor consisted of six levels, including conservation tillage by Combinate, no-tillage by Baldan grain drill, conservation tillage by Chizelpacker, conservation tillage by Delta Model, surface tillage by heavy disk, and conventional tillage by moldboard plow and twice disk. Secondary factor included two levels of sulfosulfuron application(with and without sulfosulfuron). Soil samples were taken at 6 stages and soil microbial respiration and soil pH were measured as factors affecting sulfosulfuron persistence. Results showed the least time of sulfosulfuron persistence belonged to the cultivation system of no-tillage by Baldan grain drill with a half-life of 4.62 d. Then, conservation tillage by Combinate and conventional tillage with a half-life of 6.30 d and conservation tillage by Delta Model with a half-life of 9.90 d were ordered. The most time of sulfosulfuron persistence(11.55 d) was related to conservation tillage by Chizelpacker. Ninety percent reduction of sulfosulfuron concentration occurred 15.34, 20.92, 32.88, and 36.38 d after sulfosulfuron application, respectively, for no-tillage system, conservation tillage by Combinate and conventional tillage, conservation tillage by Delta Model and surface tillage, and conservation tillage by Chizelpacker. In all the cultivation systems, toxicity symptoms were not observed 40 d after spraying sulfosulfuron onto the tomato plants which were used as test plant. Effects of different cultivation systems on soil microbial respiration were also significant.