Crop Residue Application Research Articles

Biochar and crop residue application to soil: effect on soil biochemical properties, nutrient availability and yield of rice (Oryza sativa L.) and wheat (Triticum aestivum L.)

ABSTRACTIn the recent past, biochar and crop residues have attracted lots of attention as a viable strategy for maintaining soil health. This paper evaluates the comparative effect of two different doses (equivalent to 2 and 5 t C ha−1) of each of pine needle and Lantana biochar (PBC and LBC), wheat residue and lentil residue (WR and LR) on soil biological properties, nutrient availability and yield of rice and wheat in pot culture. Energy-dispersive X-ray spectroscopy (EDS) revealed higher C content of biochar than crop residues. Evaluation of biochemical quality reflected high recalcitrance indices of C and N for both PBC and LBC. Application of LBC and PBC increased the wheat grain yield significantly by 6.2%–24.2% over control. Both PBC and LBC significantly increased N and P uptakes in grain over the control and crop residues. Both biochars recorded a significant decrease of 33.9 and 71,7% in β-glucosidase activity in comparison to control at termination of study. PBC and LBC also resulted in more soil available N, P and K in soil at different intervals. The geometric mean of enzyme activities (GMea) reflected improved soil quality by PBC and LR and reduction by LBC application.

Estimation of Maize Residue Cover Using Landsat-8 OLI Image Spectral Information and Textural Features

The application of crop residue has become increasingly important for providing a barrier against water and wind erosion and improving soil organic matter content, infiltration, evaporation, temperature, and soil structure. The objectives of this work were to: (i) estimate maize residue cover (MRC) from Landsat-8 OLI images using seven vegetation indices (VIs) and eight textural features; and (ii) compare the VI method, textural feature method, and combination method (integration of textural features and spectral information) for estimating MRC with partial least squares regression (PLSR). The results showed that the normalized difference tillage index (NDTI), simple tillage index (STI), normalized difference index 7 (NDI7), and shortwave red normalized difference index (SRNDI) were significantly correlated with MRC. The MRC model based on NDTI outperformed (R2 = 0.84 and RMSE = 12.33%) the models based on the other VIs. Band3mean, Band4mean, and Band5mean were highly correlated with MRC. The regression between Band3mean and MRC was stronger (R2 = 0.71 and RMSE = 15.21%) than those between MRC and the other textural features. The MRC estimation accuracy using the combination method (R2 = 0.96 and RMSE = 8.11%) was better than that based on only the VI (R2 = 0.88 and RMSE = 11.34%) or textural feature (R2 = 0.90 and RMSE = 9.82%) methods. The results suggest that the combination method can be used to estimate MRC on a regional scale.

Effect of organics, biofertilizers and crop residue application on soil microbial activity in rice – wheat and rice-wheat mungbean cropping systems in the Indo-Gangetic plains

AbstractThe aim of this study was to investigate the response of soil microbial parameters to nutrient management practices involving organic amendments, farmyard manure (FYM), vermicompost (VC), crop residues (CR) and biofertilizers (BF) in rice–wheat and rice–wheat–mung bean cropping system of the Indo-Gangetic Plains, India. Soil microbial biomass C (Cmic), basal respiration, ergosterol, glomalin, soil enzymes (glucosidases, phosphatases and dehydrogenases), FDA activity, organic carbon (Corg), Cmic-to-Corg ratio and metabolic quotient (qCO2) were estimated in soil samples collected at 0–15 cm depth. The highest Corg (0.64%) and Cmic (103.8 μg g−1) soil levels occurred in the treatment receiving a combination of VC, CR and BF. Soil respiration, Corg and Cmic-to-Corg ratio were significantly enhanced by the input of CR to plots receiving FYM and VC. The qCO2 was the highest in plots receiving a combination of FYM, CR and BF followed by control (no nutrient input) and least in plots receiving a combinati...

The effects of tillage, mulching and termite control strategies on termite activity and maize yield under conservation agriculture in Mozambique

Conservation Agriculture (CA) is a farming system premised on minimum soil disturbance, provision of permanent soil cover and the use of crop rotation/associations. However, in central Mozambique, provision of permanent soil cover is threatened by termites which feed on the residues. This study investigated the effectiveness of tillage and mulch management in CA as well as termite control strategies including local natural indigenous techniques on termite activity, crop lodging and maize (Zea mays L.) yields. The study was carried out at a research site in Chimoio, Central Mozambique over two seasons, 2011/12 and 2012/13. The application of crop residues in CA significantly increased (p < 0.05) termite activity measured through surface area covered by termite galleries (termite activity) from 6.4 to 11.5% and termite numbers per litter bag from 78 to 138 in fields without and with residues, respectively. Residue application also reduced maize crop lodging due to termite attack as the termites preferentially fed on the maize residues. However, tillage effects alone on termite activity were not apparent. Maize yield increased significantly on switching from conventional tillage to minimum soil disturbance (no till) but not with residue application. With respect to the termite control methods tested, only the commercial insecticide fipronil (phenylpyrazole) proved to be effective in reducing termite consumption of residues and also significantly reduced lodging of maize plants at harvest. At least 1.5 t ha−1 of the residues remained in the system where fipronil was applied in comparison to 0.41–0.48 t ha−1 in the other treatments by November 2013. Maize grain yields were negatively correlated (p < 0.05) to crop lodging due to termite damage while crop lodging in turn declined significantly with application of surface residues. Termite activity was however not significantly correlated to crop lodging, suggesting that termite activity could increase without necessarily increasing crop lodging. Thus in cases where termite damage increases to pest proportions, commercial control insecticides such as fipronil, offer a possible solution to control termites but its economic and long term environmental effects need to be evaluated.

Sensitivity of Labile Soil Organic Carbon Pools to Long-Term Fertilizer, Straw and Manure Management in Rice-Wheat System

Labile soil organic carbon (SOC) pools, estimated through chemical fractionation techniques, are considered sensitive indicators of management-induced changes in quality and composition of soil organic matter. Although the impacts of organic manure and crop residue applications on C sequestration in rice-wheat system are fairly well documented, their influence on labile SOC pools is relatively less known. Impacts of organic manure, rice straw, and inorganic fertilizer nitrogen (N) applications on soil total organic carbon (TOC) and SOC pools including water-extractable organic C (WEOC), hot water-soluble organic C (HWOC), potassium permanganate-oxidizable organic C (KMnO4-C), microbial biomass C (MBC), mineralizable organic C (Cmin), and the oxidizable fractions of decreasing oxidizability (easily-oxidizable, oxidizable, and weakly-oxidizable) were investigated in an 11-year field experiment under rice-wheat system. The field experiment included treatments of different combinations of farmyard manure, rice straw, and fertilizer N application rates, with C inputs estimated to be in the range from 23 to 127 Mg ha−1. After 11 years of experiment, WEOC, HWOC, and KMnO4-C were 0.32%–0.50%, 2.2%–3.3%, and 15.0%–20.6% of TOC, respectively. The easily-oxidizable, oxidizable, and weakly-oxidizable fractions were 43%–57%, 22%–27%, and 10%–19% of TOC, respectively. The applications of farmyard manure and rice straw improved WEOC, HWOC, KMnO4-C, easily-oxidizable fraction, Cmin, and MBC, though the rates of change varied considerably from –14% to 145% and –11% to 83% of TOC, respectively. At the C input levels between 29 and 78 Mg C ha−1 during the 11-year period, the greatest increase was observed in WEOC and the minimum in KMnO4-C. Water-extractable organic C exhibited a relatively greater sensitivity to management than TOC, suggesting that it may be used as a sensitive indicator of management-induced changes in soil organic matter under rice-wheat system. All the other labile SOC pools exhibited almost the same sensitivity to management as TOC. Most of the SOC pools investigated were positively correlated to each other though their amounts differed considerably. Long-term applications of farmyard manure and rice straw resulted in build-up of not only the labile but also the recalcitrant pool of SOC, emphasizing the need for continued application of organic amendments for permanence of the accrued C under the experimental conditions.

Effect of humic acid and crop residue application on emergence and wheat phenology

Effect of humic acid and crop residue application on emergence and wheat phenology

Effect of conservation tillage and supplemental drip irrigation on growth, yield attributes and yield ofBtcotton

Field experiments were conducted at Cotton Research Station, Veppanthattai during 2012–13 and 2013–14 to carry out the studies on tillage with crop residues and supplemental irrigation through drip system on rainfed Bt cotton. The experiments were laid out in a strip plot design with three replications. The main plot treatments were conventional tillage, minimum tillage without crop residue, minimum tillage with crop residue @ 2.5 t/ha and minimum tillage with crop residue @ 5 t/ha. Conventional tillage comprised one disc ploughing, four cultivator ploughings and two harrowings (0.3–0.4 m deep). Minimum tillage included only one ploughing (cultivator) and two harrowings (0.1–0.12 m deep). The sub-plot comprised irrigation treatments viz., supplemental drip irrigation through drip system one, two and three times and without irrigation (control) during the cropping period. Under paired row planting system (120+30 x 60 cm spacing), one 12 mm lateral was laid out between two rows of Bt cotton. The supplemental irrigations were given to the crops at the time of moisture stress period determined based on the visual symptoms of wilting. Recommended dose of fertilizers viz., 120: 60: 60 kg NPK/ha was applied to Bt cotton. The results revealed that minimum tillage (BBF) with crop residue application @ 5 t/ha (M4) recorded higher plant height, dry matter production, LAI, number of sympodial branches/plant, number of bolls/plant and seed cotton yield.

Effect of crop residue and residual zinc on zinc fractions and their contribution to zinc uptake under rice-wheat cropping system in calciorthents

The long term effect of crop residue and residual zinc on Zn fractions in soil and their contribution to Zn uptake in rice-wheat system was studied in calciorthents of the Rajendra Agricultural University, Pusa, Samastipur (Bihar) during 2010–11 and 2011–12. Application of zinc and crop residue increased the water soluble+exchangeable, complexed, organically bound, carbonate and amorphous oxide, crystalline oxide, residual and total Zn in the soil. The order of dominance of different fractions in soil was total Zn (164.35 mg/kg)> residual-Zn (156.41 mg/kg) >Zn bound to crystalline oxide (3.06 mg/kg)>complexed Zn (2.27 mg/kg)>organically bound Zn (1.14 mg/kg)> water soluble plus exchangeable Zn (0.84 mg/kg) and Zn bound carbonate and amorphous oxide (0.73 mg/kg). All the soil Zn fractions were significantly correlated among themselves indicating existence of a dynamic equilibrium with each other. Zinc uptake by rice-wheat was improved with zinc along with crop residue plus compost. Among different Zn fractions, Zn bound to crystalline oxide, followed by Zn bound to carbonate and amorphous oxide played a key role in explaining the variation in yield and nutrient uptake by rice and wheat. The highest zinc uptake by rice and wheat was reported with the conjoint use of 100% crop residue and 10 kg Zn/ha.

Performance of cotton under organic production system

The field experiment was carried out at MARS, Dharwad during kharif 2010–11 and 2011–12 to study the impact of organic farming practices on yield and economics of organic production system. The results of two years’ pooled data revealed that combined application of compost (50%)+vermicompost (50%) equivalent to RDF+green leaf manure as mulch with application of jeevamrutha @ 500 l/ha recorded higher kapas yield (1640 kg) and it was superior over RDF alone (1522 kg/ha). Combined application of crop residue (50%)+vermicompost (50%) equivalent to RDN with lucerne with jeevamrutha @ 500 l/ha surface application recorded significantly higher net returns (Rs. 60009/ha) over other combinations.

Yellow River Sediment as a Soil Amendment for Amelioration of Saline Land in the Yellow River Delta

AbstractSoil salinization and sedimentation in the Yellow River Delta pose significant environmental concerns in China. This study demonstrated for the first time that the Yellow River sediment can be used as a soil amendment to remediate the salt‐affected soil. Four treatments including the control (CK), Yellow River sediment application at 70 Mg ha−1 (S70) and 140 Mg ha−1 (S140), and crop residue application at 3 Mg ha−1 (P3) were replicated in two blocks in the field. Cotton, one of the most common crops in the Yellow River Delta, was planted. Soil physical properties and electrical conductivity (EC) were measured. The results indicated that mixing the Yellow River sediment, a poorly graded sand, with the clayed saline soil improved soil texture, macroporosity, and saturated hydraulic conductivity. Mean EC of treated soils was significantly lower than for the control. Improved cotton emergence and stand establishment were observed along with a significant treatment effect on cotton yield. The effects of S140 and P3 on soil macroporosity, hydraulic conductivity, soil EC, and cotton growth were comparable. This study concluded that applying Yellow River sediment in the saline land is a technically feasible and environmentally sustainable approach for saline soil remediation in the Yellow River Delta. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Contrasting Effects of Sorghum Biochars and Sorghum Residues on Soil Chemical Changes of Coastal Plains Ultisols With Winter Wheat

Although most soil properties were improved following application of crop residues and/or pyrolyzed crop residues, there is still a need to pursue additional research that will improve our understanding of the impact of soil fertility enhancement because the effect could vary greatly between uncharred sorghum (Sorghum bicolor L.) residues and pyrolyzed sorghum residues (SR). We hypothesized that sorghum biochars (SB) would deliver more significant impact on soil chemical changes than SR. The objective of this study was to evaluate the contrasting effects of SR and SB with or without supplemental inorganic P on soil chemical changes of Coastal Plains Ultisols with winter wheat. The application rates for SR and SB based on 13.5 Mg ha−1 yield goal for wheat were 13,000 and 5,200 kg · ha−1, respectively. Inorganic P was added at the rate of 40 kg P · ha−1. Our results fully support our hypothesis that SB would deliver more positive effect on the changes of soil chemical properties than the SR. Most of the chemical properties of soils were significantly affected by sorghum treatments (SB + SR) and also varied widely between soil types. Overall, application of SB had small, but significant effects on soil pH, soil electrical conductivity, total carbon, and total nitrogen. Quite notably was the significant difference of these soil properties between soil types. Other aspects of soil chemical changes including extractable P, K, Ca, Mg, Al, and Fe were significantly affected by sorghum treatments. Our results have demonstrated widely differing and contrasting effects between SB and SR on changes in soil chemical properties of Coastal Plains Ultisols.

Wheat straw and its biochar had contrasting effects on soil C and N cycling two growing seasons after addition to a Black Chernozemic soil planted to barley

Application of crop residues and its biochar produced through slow pyrolysis can potentially increase carbon (C) sequestration in agricultural production systems. The impact of crop residue and its biochar addition on greenhouse gas emission rates and the associated changes of soil gross N transformation rates in agricultural soils are poorly understood. We evaluated the effect of wheat straw and its biochar applied to a Black Chernozemic soil planted to barley, two growing seasons or 15 months (at the full-bloom stage of barley in the second growing season) after their field application, on CO2 and N2O emission rates, soil inorganic N and soil gross N transformation rates in a laboratory incubation experiment. Gross N transformation rates were studied using the 15N isotope pool dilution method. The field experiment included four treatments: control, addition of wheat straw (30 t ha−1), addition of biochar pyrolyzed from wheat straw (20 t ha−1), and addition of wheat straw plus its biochar (30 t ha−1 wheat straw + 20 t ha−1 biochar). Fifteen months after their application, wheat straw and its biochar addition increased soil total organic C concentrations (p = 0.039 and <0.001, respectively) but did not affect soil dissolved organic C, total N and NH4 +-N concentrations, and soil pH. Biochar addition increased soil NO3 −-N concentrations (p = 0.004). Soil CO2 and N2O emission rates were increased by 40 (p < 0.001) and 17 % (p = 0.03), respectively, after wheat straw addition, but were not affected by biochar application. Straw and its biochar addition did not affect gross and net N mineralization rates or net nitrification rates. However, biochar addition doubled gross nitrification rates relative to the control (p < 0.001). Our results suggest that land application of biochar, as opposed to the application of the raw wheat straw, could suppress CO2 and N2O emissions and enhance soil C sequestration. However, the implications of the increased soil gross nitrification rate and NO3 −-N in the biochar addition treatment for long-term NO3 −-N dynamics and N2O emissions need to be further studied.

Productivity, Organic Carbon and Residual Soil Fertility of Pigeonpea–Wheat Cropping System Under Varying Tillage and Residue Management

Conservation agriculture improves productivity and soil quality, but most of the research results are only confined to the rice–wheat system. Hence, a long term field experiment was conducted at Indian Agricultural Research Institute, New Delhi during 2008–2009 to 2011–2012 on a sandy loam soil to study the effect of tillage and crop establishment techniques, and residue management practices on system productivity, residual nutrient status, microbial biomass carbon, microbial biomass nitrogen and enzymatic activities under a pigeonpea–wheat cropping system. It was observed that zero tillage gave 5.4 and 2.3 % higher pigeonpea and wheat yield, respectively, over conventional tillage. Similarly, it resulted in 9.6 and 4.9 % higher Kjeldahl N and extractable K, respectively and the plots under zero tillage had 20.6, 8.0 and 6.1 % higher dehydrogenase and acid and alkaline phosphatase activities, respectively, over conventional tillage. Application of crop residue at 3 t/ha provided 14.3 and 34.4 % higher pigeonpea and wheat grain yield, respectively, over no residue. Further, organic C, Kjeldahl N and Olsen’s P in soil were enhanced by 7.4, 6.9 and 7.5 %, respectively, due to residue compared to no residue plots. Combined application of pigeonpea + wheat residue at 3 t/ha resulted in higher dehydrogenase (20.9 µg triphenylformazan/g/h), β-glucosidase (145 µg p-nitrophenol/g/h), and acid phosphatase activities (24.5 µg p-nitrophenol/g/h) than the single application of wheat or pigeonpea residue in either season or no residue control.

EFFECT OF TILLAGE AND RESIDUE MANAGEMENT ON PRODUCTIVITY OF SOYBEAN AND PHYSICO-CHEMICAL PROPERTIES OF SOIL IN SOYBEAN-WHEAT CROPPING SYSTEM

A microplot experiment was conducted in soybean–wheat cropping system at New Delhi during 2010-11 and 2011-12 to study the effect of continuous or cyclic tillage, viz., conventional tillage (CT) and zero-tillage (ZT) and residue management of either soybean (SR) and/or wheat (WR) on yield performance and soil physico-chemical properties. The experiment was laid out in randomized block design with two replications in microplots of size 4×1.4 m. Plant height of soybean was influenced due to tillage and residue management at different growth stages. All yield attributes of soybean were showed variation due to treatments. The harmful effects of ZT on yield attributes could be overcome with residue application on soil surface. The results indicated that tillage and residue management to the immediate crop of soybean was more important for increasing grain yield (26%) and stover production (32%) of soybean and the residual effect of residue to previous soybean was relatively small. The change in organic C was relatively small even with regular addition of crop residues. There was no change in available nutrients (N, P and K) due to tillage and residue management treatments. The variation in soil physical properties was also small and a significant improvement may be expected over several years of continuous application of crop residue and ZT.

Combined impacts of climate and nutrient fertilization on yields of pearl millet in Niger

Effects of climate variability and change on yields of pearl millet have frequently been evaluated but yield responses to combined changes in crop management and climate are not well understood. The objectives of this study were to determine the combined effects of nutrient fertilization management and climatic variability on yield of pearl millet in the Republic of Niger. Considered fertilization treatments refer to (i) no fertilization and the use of (ii) crop residues, (iii) mineral fertilizer and (iv) a combination of both. A crop simulation model (DSSAT 4.5) was evaluated by using data from field experiments reported in the literature and applied to estimate pearl millet yields for two historical periods and under projected climate change. Combination of crop residues and mineral fertilizer resulted in higher pearl millet yields compared to sole application of crop residues or fertilizer. Pearl millet yields showed a strong response to mean temperature under all fertilization practices except the combined treatment in which yields showed higher correlation to precipitation. The crop model reproduced reported yields well including the detected sensitivity of crop yields to mean temperature, but underestimated the response of yields to precipitation for the treatments in which crop residues were applied. The crop model simulated yield declines due to projected climate change by −11 to −62% depending on the scenario and time period. Future crop yields in the combined crop residues+fertilizer treatment were still larger than crop yields in the control treatment with baseline climate, underlining the importance of crop management for climate change adaptation. We conclude that nutrient fertilization and other crop yield limiting factors need to be considered when analyzing and assessing the impact of climate variability and change on crop yields.

Impact of irrigation and crop residue management on maize (Zea mays)– chickpea (Cicer arietinum) sequence under no tillage conditions

A field experiment was conducted during 2007-08 and 2010-11 at Belvatagi, Karnataka to study the effect of irrigation and crop residue mulching on water use efficiency and yield of maize (Zea mays L.) - chickpea (Cicer arietinum L.) sequence under no tillage condition. In this experiment, three irrigation levels (0.8, 0.6 and 0.4 IW/CPE ratio) were combined with or without crop residue in no tillage situation in split plot design and compared with tillage control. Maize and chickpea grain yields were significantly influenced by irrigation. Application of crop residue did not affect the maize and chickpea but affected the maize - chickpea sequence as a whole. No till maize grain yield was higher with 0.6 IW/CPE ratio with residues (8.68 tonnes/ha) and was on par with tilled maize (8.69 tonnes/ha). This treatment also recorded higher water use efficiency (18.43 kg/ha-mm). No tillage significantly reduced the chickpea grain yield in comparison to normal tillage; but improved the water use efficiency. No tilled maize - chickpea sequence required irrigation at 0.6 IW/CPE ratio with crop residue application @ 5 tonnes/ha for maize and 0.4 IW/CPE with residue for chickpea was found better for higher yield and water use efficiency.

Impact of long-term application of manure, crop residue, and mineral fertilizer on organic carbon pools and crop yields in a Mollisol

Purpose While the influence of integrated fertility management systems on yield and N cycling in Mollisols is documented, its effect on soil C sequestration remains to be determined. We examined the response of organic C pools and crop yields to 21 years’ organic amendments applied at relatively low rates in a high-C Mollisol to optimize win–win management practices that balance agronomic and environmental interests.

Preceding crops and residue management practices on performance of mustard under zero-till semi-arid condition

A field experiment was conducted in 2010/11 and 2011/12 at New Delhi to study the performance of zero-till rainfed mustard. The influence of preceding rainy season crops, viz. pearl millet, cluster bean and green gram; and residue management, viz. no residue, crop residue and Leucaena twigs mulching on this mustard crop was observed. Pooled analysis of mustard seed yield was significantly higher (+51%) in 2010/11 (1.80 t/ ha) than 2011/12 (1.19 t/ha) due to favourable weather condition in the first year. Further, Leucaena twigs mulching resulted higher seed yield of 2.17 t/ha in 2010/11 than 1.94 t/ha in 2011/12. Green gram as preceding crop resulted significantly higher mustard yield in 2010/11, while it was higher after cluster bean in 2011/12. Interaction between crop residue and preceding rainy season crops on growth parameters exerted significant variations, while yield attributes showed the mixed response. Cluster bean with Leucaena twigs led to higher yield of mustard, followed by green gram with crop residue. Economic analysis exhibited the highest net return of mustard grown after cluster bean with Leucaena twigs mulching. From the findings it is observed that growth indices, yield, and yield attributes and economics of mustard were influenced significantly by preceding crops and crop residue application. The effect of Leucaena twigs was found better in 2010/11, while both crop residues and Leucaena twigs mulching were equally effective in 2011/12. Cluster bean as preceding crop to mustard resulted higher yield and net returns, followed by green gram and cluster bean with crop residues. It was suggested that mustard after cluster bean with Leucaena twigs was a high yielding and profitable cropping system under zero-till semi-arid condition. It was concluded that growing mustard after cluster bean with Leucaena twigs mulching resulted increased yield and profitable cropping system for rainfed areas in zero-till semi arid condition of New Delhi. Agronomy Journal of Nepal (Agron JN) Vol. 3. 2013, Page 23-32 DOI: http://dx.doi.org/10.3126/ajn.v3i0.8983

Sugarcane Crop Residue Increases N2O and CO2 Emissions Under High Soil Moisture Conditions

Sugarcane crop residues from green cane harvests may affect the greenhouse gas fluxes from the soils. Therefore, it is important to understand how changes in soil moisture covered with cane trash alter the N2O and CO2 emission. The aim of this study was to evaluate N2O and CO2 emission from repacked soil columns incubated with (16 Mg ha−1) or without crop residues and N fertilizer (0 or 2.1 g N m−2), and as a function of four soil moisture levels (25, 50, 75 and 100 % of water holding capacity). For gas samplings, the columns were closed with a lid and four gas samples were taken in 20 min. The N2O fluxes increased linearly (p < 0.01) with increasing soil moisture regardless of the residue application on soil. However in the columns with trash the moisture effect, on N2O emission rates, was two-fold greater. Every 10 % increase in moisture in relation to the holding capacity resulted in losses equivalent to 790 and 1,640 μg N m−2 for the 0 and 16 Mg ha−1 crop residue rates, respectively. In conditions of low moisture (25 and 50 %), the crop residue did not increase emissions compared to the bare soil. The CO2 emission also was linearly stimulated with increasing soil moisture, regardless of crop residue application. However, the CO2 emission rate was higher with the residue. Our study indicates that the effects of crop residue on greenhouse gas emissions are exacerbated in periods with high soil moisture.

Crop residue incorporation alters soil nitrous oxide emissions during freeze—thaw cycles

Pelster, D. E., Chantigny, M. H., Rochette, P., Angers, D. A., Laganiere, J., Zebarth, B. and Goyer, C. 2013. Crop residue incorporation alters soil nitrous oxide emissions during freeze-thaw cycles. Can. J. Soil Sci. 93: 415-425. Freeze-thaw (FT) cycles stimulate soil nitrogen (N) and carbon (C) mineralization, which may induce nitrous oxide (N2O) emissions. We examined how soybean (Glycine max L.) and corn (Zea mays L.) residue incorporation affect N2O emissions from high C content (35 g kg-1) silty clay and low C content (19 g kg-1) sandy loam soils over eight 10-d FT cycles, as a function of three temperature treatments [constant at +1°C (unfrozen control), +1 to -3°C (moderate FT), or +1 to -7°C (extreme FT)]. In unamended soils, N2O emissions were stimulated by FT, and were the highest with extreme FT. This was attributed to the increased NO3 availability measured under FT. Application of mature crop residues (C:N ratios of 75 for soybean and 130 for corn) caused rapid N immobilization, attenuating ...