Residue Removed Research Articles

Yield and yield components of common bean as influenced by wheat residue and nitrogen rates under water deficit conditions

Incorporation of crop residues into agricultural system has become a worldwide efficient practice for enhancing crop production. The main objectives of this experiment was to investigate the major role of incorporating wheat ( Triticum aestivum L.) residues and nitrogen (N) fertilizers rates under different water requirements (WR) on growth, seed yield and yield components of common bean ( Phaseolus vulgaris L.). The results showed that seed yield under 80% WR in retained crop residue plots was ∼ 11% higher than WR treatment with no residue incorporation. Seed yield was not significantly different between residue retention and removal treatments in 2016, whereas it was higher (12% and 17%) under residue retained plots compared to removed ones in subsequent years. Seed yields responded to N up to 170 and 225 kg ha −1 in removed and retained residue treatments, respectively in 2017 and 2018. Annual increment of seed yield in residue retained plots (36%) was 2.11 times higher than the residue removed ones (17%). There was higher soil N content in 50% residue retention with 225 kg N ha −1 under both water deficit treatments in all years. The highest soil organic carbon (SOC) was achieved with normal irrigation in retained residue plots with 225 kg N ha −1 in all years. Overall, wheat residue incorporation into the soil and N-supply substantially contributed to counteracting yield declines of common bean under water deficit conditions. • Wheat residue incorporation into soil improved soil characteristics. • Wheat residues incorporation stored higher SOC and N than removed ones. • Application of wheat residue in combination with N fertilization enhancing bean growth. • Wheat residues application with sufficient N rates ameliorating water stress condition.

Evaluation of maximum wall shear stress from air impingement to remove food deposits from stainless steel surfaces

The risk of cross-contamination during manufacturing of low water activity foods requires careful attention to cleaning and sanitation. Considering the challenges encountered in such manufacturing, air impingement can provide a unique approach to remove deposits from the food-contacted surface, particularly, the crevices or cracks. The objective of this study was to evaluate the shear stress-induced by air jet impingement for removal of food residues. The wall shear stress distribution on a surface below an air jet was measured using oil-film interferometry. The air impingement was operated at three level of air velocity (Reynolds number = 7756, 13,444, and 18,787) and three different nozzle height (24 (H/D = 6), 32 (H/D = 8), 40 mm (H/D = 10)). The shear stress was found to become higher along with the increase of air velocity and decrease of nozzle height. The observed distribution of wall shear stress on the surface was fitted using the Gaussian model and Polynomial model. The Gaussian model appeared to be preferable according to the statistical analysis, which aligned with previous literature. Based on the Gaussian model, the maximum wall shear stress was estimated. The maximum wall shear stress increased with Reynolds number ( Re ) and the ratio of jet height to jet nozzle diameter. The highest maximum shear stress (10.74 Pa) occurred at a Reynolds number of 18,787 and a height of 24 mm (H/D = 6). This trend was directly correlated with removal efficiency. The greatest removal of the treatment was achieved by 40% at maximum wall shear stress. A linear relationship between percent residue removed and maximum wall shear stress was obtained from the experimental results, and a threshold maximum wall shear stress of 2.73 Pa has been proposed for removal of peanut butter residue from a stainless-steel surface. The current study demonstrates the promising of the air impingement in the cleaning operation for low water activity food. • Wall shear stress increased with an increase in velocity and decrease in height. • Removal of food deposits revealed a similar trend to velocity and height. • Linear relation was found between maximum shear stress and food removal.

Impacts of corn stover management and fertilizer application on soil nutrient availability and enzymatic activity

Corn stover is a global resource used in many industrial sectors including bioenergy, fuel, and livestock operations. However, stover removal can negatively impact soil nutrient availability, especially nitrogen (N) and phosphorus (P), biological activity, and soil health. We evaluated the effects of corn stover management combined with N and P fertilization on soil quality, using soil chemical (nitrate, ammonium and Bray-1 P) and biological parameters (β-glucosidase, alkaline phosphatase, arylsulfatase activities and fluorescein diacetate hydrolysis—FDA). The experiment was performed on a Mollisol (Typic Endoaquoll) in a continuous corn system from 2013 to 2015 in Minnesota, USA. The treatments tested included six N rates (0 to 200 kg N ha−1), five P rates (0 to 100 kg P2O5 ha−1), and two residue management strategies (residue removed or incorporated) totalling 60 treatments. Corn stover management significantly impacted soil mineral-N forms and enzyme activity. In general, plots where residue was incorporated were found to have high NH4+ and enzyme activity compared to plots where residue was removed. In contrast, fields where residue was removed showed higher NO3− than plots where residue was incorporated. Residue management had little effect on soil available P. Soil enzyme activity was affected by both nutrient and residue management. In most cases, activity of the enzymes measured in plots where residue was removed frequently showed a positive response to added N and P. In contrast, soil enzyme responses to applied N and P in plots where residue was incorporated were less evident. Soil available nutrients tended to decrease in plots where residue was removed compared with plots where residue was incorporated. In conclusion, stover removal was found to have significant potential to change soil chemical and biological properties and caution should be taken when significant amounts of stover are removed from continuous corn fields. The residue removal could decrease different enzymes related to C-cycle (β-glucosidase) and soil microbial activity (FDA) over continuous cropping seasons, impairing soil health.

Nutrient Accumulation Affected by Corn Stover Management Associated with Nitrogen and Phosphorus Fertilization

Bio-ethanol production from corn stover harvest would change nutrient removal, in particular nitrogen (N) and phosphorus (P), affecting nutrient replenishment and corn development under field-grown conditions. This research was developed to investigate whether stover removal had any influence on the amount of N and P fertilizer required for maximum corn production in the United States (US) Midwest in a stover removal scenario. This study was conducted in Lamberton, MN on a Typic Endoaquoll under continuous corn from 2013 to 2015. The treatments included six N rates (0 to 200 kg N ha−1 in 40 kg increments), five P rates (0 to 100 kg P2O5 ha−1 in 25 kg increments), and two residue management strategies (residue removed or incorporated). Residue management was found to have a significant impact on corn response to N and P application. We verified that residue-removed plots yielded more and therefore required more N and P application from fertilizers. Grain yield after residue was removed was greatest with the highest N and P2O5 rates, whereas grain yield after residue was incorporated was greatest with intermediate N and P2O5 rates in 2013 and 2014. In 2015, residue management did not significantly affect grain yield. Grain N and P accumulation followed a similar behavior as that observed for grain yield. In general, residue removal decreased nutrient availability, while in the residue-incorporated treatment, those nutrients were returned. Although the results of the study showed potential for biomass harvest, it also indicated that nitrogen immobilization and nutrient depletion from the soil could be a limiting factor.

The Crop Residue Removal Threshold Ensures Sustainable Agriculture in the Purple Soil Region of Sichuan, China

Sichuan, a hilly area in southwestern China, is recommended as a bioethanol production base because of its abundant crop residue resources. However, removing the crop straw for bioethanol may negatively affect soil fertility and productivity due to the local purple soil vulnerability. To explore the impact of crop residue removal on soil fertility and productivity and meet the needs of sustainable agriculture, we conducted a crop residue removal experiment by measuring the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, and crop yield in the purple soil region in southwest China. Soil erosion was also simulated by Revised Universal Soil Loss Equation version 2 (RUSLE 2). The results showed that soil erosion increased with the increase of the straw removal rate. Compared with 0% removal treatment, the SOC content reduced at other removal rate treatments, especially for long-term residue removal. The effect of residue removal on soil TN and TP was not consistent within one year. After two years, residue removal greater than 25% caused a decrease in TN by 1.6–3.7%, and straw removal greater than 50% caused a TP decrease by 8.5–9.3%. More than 25% of the residue removed reduced maize and canola yields, and TN and TP content. However, all crop residue removal treatments resulted in SOC content reduction and soil erosion deterioration. In conclusion, crop residue removal was not recommended due to agricultural sustainability in Sichuan, China.

English

A field experiment was conducted in three factorial strip-split-plot design to evaluate the effect of two establishment methods (EM) [transplanted in puddled soil (PuTPR) and direct seeded in zero tillage (ZT-DSR)], two residue levels [residue kept at 3 t ha-1 (RK) and residue removed (RR)] with two nitrogen doses [recommended dose (100 kg N ha-1) (RD) and farmers' dose (50 kg N ha-1) (FD)] with six replications on rice variety “Ramdhan” during the year 2016. PuTPR, RK, and RD of nitrogen had taller plant height in almost all the days of observation. Similarly, the number of tillers per square meter and leaf area index was significantly higher in ZT-DSR and RD of nitrogen in all the days of observation. Number of effective tillers (ET) and sterility percentage were significantly higher in ZT-DSR but thousand grain weight (TGW), grain per panicle and panicle weight were significantly higher in Pu-TPR. Residue incorporation produced more number of ET. ET, TGW, panicle length and weight were significantly higher in RD. Days to heading and physiological maturity was significantly lower in PuTPR than ZT-DSR. Grain yield was significantly higher in residue kept treatment and recommended nitrogen dose. Key words: Conservation agriculture, direct seeded rice, leaf area, nitrogen, sterility, tiller.

Cover crop and crop residue removal effects on temporal dynamics of soil carbon and nitrogen in a temperate, humid climate.

Quantification of seasonal dynamics of soil C and N pools is crucial to understand the land management practices for enhancing agricultural sustainability. In a cover crop (CC) experiment established in 2007 and repeated at an adjacent site in 2008, we evaluated the medium-term impact of CC (no cover crop control (no-CC), oat (Avena sativa L.), oilseed radish (OSR, Raphanus sativus L. var. oleoferus Metzg. Stokes), winter cereal rye (rye, Secale cereale L.), and a mixture of OSR+Rye) and crop residue management (residue removed (-R) and residue retained (+R)) on soil C and N dynamics and sequestration. Labile and stable fractions of C and N were determined at seven different time points from 0-15 cm depth during tomato (Solanum lycopersicum L.) growing season in 2015 and 2016 (referred to as site-years). As expected, over the tomato growing season in both site-years, organic C (OC) and total N did not change while the labile C and N fractions changed with greater concentrations observed at 2 weeks after tillage (WAT) and greater treatment differences observed for seven out of eleven soil attributes at tomato harvest. Therefore, 2WAT (early June) and tomato harvest (early September) are reasonably optimum sampling times for soil C and N attributes. Seasonal variation of labile fractions suggested the potential impact of substrate availability from crop residues on soil C and N cycling. Medium-term CC usage enhanced the surface soil C and N storage. Overall, this study highlights the positive and synergistic influences of CCs and maintaining crop residues in increasing both labile and stable fractions of C and N and enhancing soil quality in a temperate humid climate.

Differential response from nitrogen sources with and without residue management under conservation agriculture on crop yields, water-use and economics in maize-based rotations

Under the present scenario of resource degradation, shortage of water & labour, growing production cost, falling water tables as well as farm profitability and climate-change; the sustainability of traditional rice-wheat (RW) system became a major challenge in Indo-Gangetic Plains (IGP). Therefore, to address these issues in India’s, north-western IGP, RW system need to be diversified with conservation agriculture (CA) based profitable and sustainable systems. Full CA based crop production technologies may furnish more yield, reduce water need and enhance farm profitability, without hampering the sustainability of natural resources. So in an established on-going long term study (since 2012), we assessed the medium term-impact of four different nitrogen management practices [Un-fertilized, N through Prilled urea (PU), N through Sulphur coated urea (SCU) and N through Neem coated urea (NCU)] in residue retained permanent bed (PB + R) vs. residue removed permanent bed (PB-R) plots under maize-mustard-mungbean (MMuMb) and maize-wheat-mungbean (MWMb) crop rotations. Results showed that, the maize, wheat and mustard yields were statistically similar in first year of study irrespective of residue retention or removal, whereas during subsequent years, yields of maize, wheat and mustard were significantly (P < 0.05) higher by 10.1–16.7%, 9.3–23.6% and 13.6–21.9% under residue retained plots (full CA) than residue removed plots (partial CA), respectively. However, the mungbean yield was significantly (P < 0.05) greater by 12.4–24.3% in residue retained plots right from first year onwards. In permanent bed plots, residue retention reduced the water requirement by 50–55 ha-mm, and improved water productivity by 9.4–27.6%, 17.7–30.4%, 21.7–42.6% and 33–57.2% in maize, wheat, mustard and mungbean, respectively compared to no residue plots. Economic profit for MMuMb (from 2nd year onward) and MWMb rotations (in all the 5-years) was significantly (P < 0.05) higher by 220–464 and 165–474 US$/ha/year, respectively in residue retained plots compared to residue removed plots. Among N management practices, application of neem and sulphur coated urea significantly improved the individual crops yield, water productivity and system profitability compared to un-fertilized both under residue retained and removed plots. However, across the cropping systems the effectiveness of different N sources varied with residue management, as the annual increment in system productivity of SCU treated and residue retained plots under MMuMb system was about thrice than the residue removed plots. Whereas, in MWMb system the annual increment in system productivity was double in NCU treated and residue retained plots as compared to residue removed plots. Effectiveness of PU was not increased with residue retention in maize and mustard, whereas in wheat both the coated and uncoated urea application increased the annual yield by manifolds. Findings of this study support differential opportunity of residue management and suggest that a combination of full CA-based MMuMb/MWMb system with use of proper N sources [like slow release coated fertilizers (NCU/SCU)] could augment the system productivity, resource-use efficiency, farm profitability, while sustaining the natural resources in Western IGP in India and other similar agro-ecologies.

Conservation Agriculture Increases Profits in an Andean Region of South America

Core Ideas Erosion is decreasing the potential for food security in the Andean region. Zero tillage would be a viable and economical practice for this region. Adding N fertilizer increased the net economic returns by 22%. These practices could potentially increase the income of 200,000 farmers. The Andean region of Ecuador is critical for the country's food security; however, cultivation of high‐slope mountainous agricultural systems that experience significant precipitation is accelerating erosion of the soils and reducing the productivity and sustainability of these systems. For 5 yr we monitored tillage and crop residue management practices using a 2 × 2 factorial randomized block (Phase 1) and a 2 × 2 factorial randomized block with split plot (Phase 2) to assess the effects of tillage, crop residue management, and N fertilization on yields and economic returns. Our study found in the initial phase that for three out of the four crops zero tillage (ZT) had higher average yields than minimum tillage, and for one of these three crops, the increase was significant. Our study found in Phase 2 that when N fertilizer was added as a treatment, compared with crops that were not fertilized, yields were significantly higher in four out of five crops. Leaving the crop residue at the surface was a practice that increased the yields of one of the five crops. The higher net economic returns for Phase 1 were with ZT and with harvesting crop residue. When N was added as a treatment in Phase 2, higher net economic returns were found with ZT and residue removed and with N fertilization. Nitrogen fertilizer, crop residue removal, and zero tillage increased net economic returns by 22, 45.1, and 31.8%, respectively. There is potential to use ZT in this region of South America.

Baling or Grazing of Corn Residue Does Not Reduce Crop Production in Central United States

Core Ideas Baling of corn residue removed three times more residue than did grazing of residue. Grazing and baling appear to have no impact on subsequent crop yields in flat, high‐yielding fields. Corn (Zea Mays L.) residue can be used by cattle producers as a source of forage that can either be grazed or baled. While many studies have evaluated the impact of baling corn residue on subsequent crops, relatively few have evaluated the effect of grazing of corn residue. An on‐farm multi‐year study (3 or 4 yr) was conducted at six sites in the central United States to determine effects of grazing or baling of corn residue on subsequent grain yield. Most sites were under no‐till management and were irrigated. Some locations were in continuous corn while others were in a corn–corn–soybean [Glycine max (L.) Merr.] or corn–soybean rotation. At each location, there were three corn residue treatments: no bale–no graze (CON), baled (BLD), and grazed (GZD) with two or three replicates per treatment. Baling and grazing management was dictated by the cooperating producer. In the spring, corn residue remaining in the CON (10.17 Mg ha−1) was greater (P &lt; 0.01; SEM ± 0.449) than both GZD (8.68 Mg ha−1) and BLD (3.60 Mg ha−1) with GZD being greater (P &lt; 0.01) than BLD. Residue management did not affect (P ≥ 0.26) subsequent grain yield (corn, soybean, or dry bean [Phaseolus vulgaris L.]). Corn yield ranged from 6.2 to 18.2 Mg ha−1 with a mean of 14.0 Mg ha−1. Results indicate that, in the short term, baling or grazing of corn residue in high grain yielding fields will not negatively impact grain yield but grazing results in less removal of residue than baling.

Removal of crude oil residue from solid surfaces using microemulsions

This paper presents a study on the removal of crude oil residue from sand using microemulsions. A newly developed experimental technique referred to as the Shaken Bottle test was developed to quantify the amount of crude oil residue removed. This technique consists of coating sand with crude oil, baking it in an oven for 24 h and then treating it with a surfactant solution or a microemulsion. The percentage of crude oil residue removal was quantified using UV–Vis spectroscopy. In this study, microemulsion removed a much larger amount of crude oil residue from sand surfaces compared to using the same surfactant alone. The amount of removal was strongly dependent on the crude oil composition, microemulsion concentration, solvent amount and type contained within the microemulsion.

Impact of Tillage and Residue Management on Water and Thermal Regimes of a Sandy Loam Soil under Pigeonpea-Wheat Cropping System

Tillage and crop residue management are the most critical components of the cultivation, which significantly affect the soil-plant-water relations. Conservation tillage (CT) aims to improve soil condition and conserve soil water, although limited information is available on seasonal variation of soil water and temperature under cropping systems. A medium duration (6 years) experiment with different tillage and residue management option on a sandy loam soil in pigeonpea-wheat cropping system was selected to monitor the changes in soil structure through adoption of conservation agriculture (CA), and the subsequent impact on soil water and thermal regimes over the growing period of wheat crop. Treatments were: conventional tillage with incorporation of previous crop residue (CT+R); conventional tillage with residue removal (CT-R); no-tillage with residue retained over surface as mulch (NT+R); and no-tillage with residue removed (NT-R). The impact was quantified in terms of change in basic soil physical parameters viz., bulk density (BD), penetration resistance (as Cone Index, CI) and porosity, and their effect on soil water dynamics, and seasonal and diurnal soil temperature. At the initial growth stages (9 to 51 DAS), NT+R and NT-R recorded 5–10 per cent higher BD at 0–10 cm layer, but was comparable with CT+R and CT-R at the later stages. Soil pore ( 30 μm) and meso-(5–30 μm) pore volumes had marginal differences. A sub-surface (10–20 cm) hard layer (CI 1.7–1.9 MPa) was omnipresent, although omission of tillage resulted in marginal reduction in CI at this layer. Marginally higher macro-pores in NT systems caused higher initial rate of infiltration and the cumulative infiltration. Throughout the growing season of wheat, NT+R retained higher soil water than other tillage-residue combinations [17% (0 to 48), 11% (−5 to 32), and 14% (−2 to 36), higher compared to NT-R, CT+R and CT-R]. Soil water content in NT+R was also higher by 20% (−5 to 41) before irrigation cycles. Similarly, soil temperature was the most regular in NT+R, even at 3 cm depth due to the presence of surface residue and higher amount of soil water. The difference between temperatures at 10 am and 3: 30 pm was 2.9 (0.2–6.3)°C in NT+R, compared to 3.8 (0.2–7)°C in NT-R, 4 (0.8–8)°C in CT+R, and 3.1 (0.7–5.5)°C in CT-R. Therefore, role of tillage and crop residues in modifying soil physical environment and maintaining better soil water and thermal conditions have been clearly documented.

Short-term effects of tillage and residue on spring maize yield through regulating root-shoot ratio in Northeast China

In recent years, yield instability of spring maize becomes increasingly pronounced under the traditional cropping system. In 2014 and 2015, short-term effects of tillage (plow-till, rotary-till and no-till) and residue (removal and incorporation) on soil properties, maize growth and yield were investigated in a brown soil region. Our results indicated that short-term reduced tillage (rotary-till and no-till) and residue incorporation promoted soil properties and maize growth. Compared with plow-till, rotary-till and no-till decreased soil bulk density and compaction below the plough layer (~30 cm). The soil organic carbon (SOC), total nitrogen and C:N of surface soil layers increased under the rotary-till (0–20 cm) and no-till (0–10 cm), which were higher in 0–30 cm soil layers for residue incorporation. For both years, root characteristics of root diameter (RAD) and root surface area density (RSD), biomass indexes of root biomass (RB), shoot biomass (SB) and root-shoot ratio (R:S) were increased under these short-term treatments. Although there were positive relationships between soil water content (SWC), C:N, RAD, RSD, RB, SB, R:S and yield, structural equation modeling showed maize yield was directly controlled by R:S. These findings will have important implications for improving the current cropping system (i.e., plow-till with residue removed) in this area.

Responses of soil properties, root growth and crop yield to tillage and crop residue management in a wheat–maize cropping system on the North China Plain

Abstract Crop residue removal and subsoil compaction are limiting to yield improvement in the North China Plain (NCP). We conducted a field study composed of six consecutive crop growing seasons from 2010 to 2013 in Henan province, China, to determine responses of soil properties, crop root distribution and crop yield to tillage and residue management in a wheat–maize cropping system under irrigated conditions. Tillage practices comprised mouldboard ploughing (MP) to a depth of 15-cm, deep mouldboard ploughing (DMP) to a depth of 30-cm, and chisel ploughing (CP) to a depth of 30-cm. Crop residue management included crop residue retained (CRRet) and crop residue removed (CRRem). The results indicated that yields in DMP and CP increased by 6.0% and 7.3% for wheat and by 8.7% and 9.0% for maize, respectively, relative to MP. The CRRet treatment also increased wheat yield by 6.7% and maize yield by 5.0%. The yield increases under DMP and CP were related to reduced bulk density and soil penetration resistance, increased soil water content, improved total N distribution and improved root density (0–60-cm). Compared with MP, the root mass density under DMP and CP were increased by 43.4% and 42.0% for wheat and by 40.6% and 39.4% for maize, respectively. The yield increases under CRRet were also related to increased soil water content, reduced penetration resistance and increased N status (0–40-cm). Overall, for DMP + CRRet and CP + CRRet, a more favorable soil environment alongside greater root mass density and suitable spatial distribution resulted in higher grain yields of wheat and maize. Thus, compared with conventional shallow tillage practice, DMP or CP with residue application could improve soil quality and agricultural productivity under irrigated areas with loam soil in the NCP.

Transition to second generation cellulosic biofuel production systems reveals limited negative impacts on the soil microbial community structure.

Currently we lack knowledge on how the soil microbial community responds to the transition from traditional grain production to cellulosic feedstock production systems with residue removal for biofuel production. Implementation of second-generation biofuel production systems could create a challenge in meeting the goal of providing cellulose biomass if the processes impact soil's function as part of ecosystem services. Our goal was to assess the transition period as we move from a grain harvest system with residue return into biomass production systems with both residue and grain removal. The existing traditional systems were continuous corn (CC) and corn–soybean rotations (corn–soybean–corn (R1) or soybean–corn–soybean (R2)). The biomass production systems include a previously established mixed tall grass prairie dominated by big bluestem (Andropogon gerardii; PR) where the above ground biomass is now harvested when it had been previously burned, corn–soybean rotations transitioned to residue recovery based on: Miscanthus×giganteus (MS), dual-purpose sorghum (Sorghum bicolor; SG), upland switchgrass (Panicum virgatum; c.v. Shawnee; SW) and a tilled continuous corn changed to continuous no-till corn (Zea mays; CR) with the residue removed. Over a three-year transition period, biological indicators of soil health included microbial biomass and community structure profile using phospholipid fatty acid (PLFA) biochemical markers, and an assessment of the saprotrophic fungal diversity using denaturing gradient gel electrophoresis (DGGE) of polymerase chain reaction amplified ITS rRNA genetic marker. Over the course of the transition, bacterial biomass dominated soils in the annual systems of CC, R1, R2, CR and SG, and the perennial system of MS. While fungal biomass dominated soils under PR. Fungal PLFA signatures and ITS-DGGE profiles demonstrated similarity between PR and the transitioned SW system, and to a lesser extent SG. In contrast, MS did not statistically alter the microbial biomass, community structure or fungal diversity away from patterns observed in the corn–soybean system. Our findings support microbial community stability and resilience as we found no negative impacts in any of the biomass recovery systems (PR, MS, SG, SW and CR) relative to the traditional systems (CC, R1 and R2), as indicated by measures of soil health. We did find that the selection of the plant types used in the biomass system could have a significant impact on the structure of both bacterial and fungal communities. With respect to soil health indicators including the fungal community, our findings suggest the dual-purpose SG system provides an encouraging alternative to continuous maize when considering plant biomass production. The selection of this dedicated perennial biomass system offers an avenue to enhance indicators of soil health and associated ecosystem services while supporting the bioenergy economy.

Tillage and corn residue harvesting impact surface and subsurface carbon sequestration.

Corn stover harvesting is a common practice in the western U.S. Corn Belt. This 5-yr study used isotopic source tracking to quantify the influence of two tillage systems, two corn ( L.) surface residue removal rates, and two yield zones on soil organic C (SOC) gains and losses at three soil depths. Soil samples collected in 2008 and 2012 were used to determine C enrichment during SOC mineralization, the amount of initial SOC mineralized (SOC), and plant C retained in the soil (PCR) and sequestered C (PCR - SOC). The 30% residue soil cover after planting was achieved by the no-till and residue returned treatments and was not achieved by the chisel plow, residue removed treatment. In the 0- to 15-cm soil depth, the high yield zone had lower SOC (1.49 Mg ha) than the moderate yield zone (2.18 Mg ha), whereas in the 15- to 30-cm soil depth, SOC was higher in the 60% (1.38 Mg ha) than the 0% (0.82 Mg ha) residue removal treatment. When the 0- to 15- and 15- to 30-cm soil depths were combined, (i) 0.91 and 3.62 Mg SOC ha were sequestered in the 60 and 0% residue removal treatments; (ii) 2.51 and 0.36 Mg SOC ha were sequestered in the no-till and chisel plow treatments, and (iii) 1.16 and 1.65 Mg SOC ha were sequestered in the moderate and high yield zone treatments, respectively. The surface treatments influenced C cycling in the 0- to 15- and 15- to 30-cm depths but did not influence SOC turnover in the 30- to 60-cm depth.

Evaluating Climate Change Mitigation and Adaptation Potential of Conservation Agriculture in Semi-arid Tropics of Southern India

Aims: As climate change related rainfall and temperature variability is being increasingly experienced in the SAT regions, we assessed climate change mitigation and adaptation potential of Conservation Agriculture (CA) by studying effects of minimum tillage (MT) and residue management practices on rain water use efficiency (RWUE), soil moisture, runoff, energy use and carbon dioxide emission in two maize-legume cropping systems. Study Design: The experiment was laid out in split-split plot design with four replications. Place and Duration of Study: The study was conducted at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) farm, Patancheru, Telangana, India during 2010-11 and 2011-12. Methodology: RWUE was calculated as maize equivalent yield divided by rainfall received during the crop season. Integrated digital runoff and soil loss monitoring unit (IDRSMU) was used to measure runoff. Soil moisture content was measured using the gravimetric method (0-30 cm depth) and neutron probe (60-90 cm depth). The soil organic carbon was analyzed following the Walkley-Black method [1]. The diesel consumption in MT and conventional tillage (CT) was estimated following Downs and Hansen (http://www.ext.colostate.edu/pubs) and emission of CO2 was estimated according to EPA, 2009 [2]. Results: Tillage and residue management practices did not show significant effect on RWUE except; CT having significantly higher RWUE over MT during 2011-12. Effect of cropping systems on RWUE was significant but variable during the two years of study. MT-RT (minimum tillage- residue retained) reduced total seasonal runoff by 28.62% and 80.22% compared to CT-RR (conventional tillage- residue removed) in 2010-11 and 2011-12, respectively. Similarly, MT-RT reduced rainwater loss and peak rate of runoff compared to CT-RR in both the years of study. During 2010, MT-RT had higher total soil moisture (v/v) in the 0-90 cm soil depth in sole as well as intercropped maize compared to CT-RR, however, during 2011 MT-RT had higher total soil moisture in sole maize only. As compared to CT, even though, MT improved SOC in 0-15 cm depth but lowered slightly in 15-30 cm depth. RT (residue retained) improved SOC in 0-15 and 15-30 cm depths compared to residue removal (RR). MT-RT had higher or equal SOC in 0-15 and 15-30 cm soil depths compared to CT-RR in both the maize-legume cropping systems. MT saved energy corresponding to 41.49 l of diesel per hectare annually compared to CT. Similarly, MT emitted 110.79 kg less CO2 annually on per hectare basis compared to CT due to reduced diesel use. Conclusion: CA, when adopted by following good agricultural practices and refined to suit the local conditions, could emerge as sustainable production system for climate change mitigation and adaptation of dryland cropping systems in semi-arid tropics of southern India.

Soil Carbon Dynamics of Transition to Pacific Northwest Cellulosic Ethanol Feedstock Production

Cellulosic ethanol commercialization promises to produce energy from agricultural biomass. Available biomass depends on plant net primary productivity (NPP) and crop type, which maintain total soil organic carbon (TOC). Effect of crop-type, residue removal, and NPP on ethanol yield and TOC levels were assessed by means of a three-pool C model derived from long-term soil incubation, acid hydrolysis, and curve fitting of a nonlinear regression model. A 2-yr field study consisting of three input regimes (Low, Medium, or High NPP), three crops [corn (Zea mays L.), wheat (Triticum aestivum, L.), and switchgrass (SG, Panicum virgatum L., cv. Blackwell)], and two harvest levels [residue removed (R) or residue not removed (NR)] was conducted near Prosser, WA, USA. After 2 yr, ethanol yield of all crops were similar under Low NPP while ethanol yield of SG under Medium and High NPP was significantly greater than that of corn or wheat under the same NPP. Switchgrass significantly contributed to active [mean residence time (MRT) 500 yr) soil C pools. Other crops had net zero or significantly reduced C pools. During a transition to cellulosic energy production, SG will contribute to soil C maintenance across a range of potential net productivity.

Greenhouse Gas Emissions from Nontilled, Permanent Raised, and Conventionally Tilled Beds in the Central Highlands of Mexico

Organic matter content increases in soil with no-tilled permanent raised beds (PBs) compared with soil with conventionally tilled beds (CBs), and this might affect greenhouse gas (GHG) emissions. Greenhouse gas (CO2, N2O, and CH4) emissions were measured from PBs, from which crop residue was either removed or retained and from CBs where crop residue was retained. The CO2 emission was not affected by tillage, but CH4 and N2O emissions were lower in PBs when residue was retained than in CBs. Removing crop residue from PBs reduced CO2 emissions compared with when it was retained, but it had no effect on N2O and CH4 emissions. The global warming potential (GWP) of GHG emissions was higher in CBs (801 kg CO2/ha/year) than in PBs (517 kg CO2/ha/year) with crop-residue retention, but more C was sequestered in the 0–60 cm soil layer in PBs (83.4 Mg C/ha) than in CBs (79.2 Mg C/ha). Crop-residue removal in PBs had little effect on the GWP of GHG compared with PBs with crop residue retained, but less C was sequestered in the latter (63.1 Mg C/ha). Net GWP (considering soil C sequestration, GHG emissions, fuel used, glyphosate application, fertilizer and seed production) was lower in CBs with crop-residue retention (1062 kg CO2/ha/year) than in PBs with crop-residue removal (6,120 kg CO2/ha/year), but it was larger than in PBs with crop-residue retention (−681 kg CO2/ha/year). We found that reduced tillage when beds were made permanent and crop-residue retention greatly reduced net GWP compared with when beds were tilled and remade each year.We found that retention of crop residue in PBs increased the emission of CO2 compared with where it was removed, but tillage did not affect fluxes of CO2. Emission of CH4 and N2O was larger from CBs than from PBs, but crop-residue management in PBs had no significant effect on fluxes of CH4 and N2O. Concentrations of mineral N were larger in CBs than in PBs, whereas the removal of crop residue from PBs increased mineral N concentration. Soil temperature was higher in CBs than in PBs and in PBs with crop residue retained compared with where it was removed. Soil water was better preserved in PBs than in CBs and in PBs where residue was retained than where it was removed. The higher water content in the PB compared with the CB will favor plant growth during dry spells. However, retaining crop residues in PBs will require sufficient application of inorganic N, as mineral N in soil is lower in PBs than in CBs or PBs with crop residue removed. Limited N availability in PBs with crop residue retained might reduce yields as poor farmers in the central highlands of Mexico apply little or no N fertilizer. Reduced tillage on PBs and crop-residue retention strongly reduced the net GWP of the system compared with the case when beds were remade each year. PBs with residue retention reduced net GWP by 50% compared with CBs with residue retention, but the removal of residues from the PBs more than doubled it.

Effects of Tillage and Residue Management on Soil Organic Carbon and Total Nitrogen in the North China Plain

A suitable tillage‐residue management system is needed in the North China Plain (NCP) that sustains soil fertility and agronomic productivity. The objectives of this study were to determine the effects of different tillage‐residue managements for a winter wheat (Triticum aestivum L.) and summer maize (Zea mays L.) double‐crop system on soil organic carbon (SOC) and total N pools. No‐tillage with residue cover (NTR), no‐tillage with residue removed and manure applied (NTRRM), and conventional tillage with residue removed (CTRR) were investigated for 6 yr, based on a uniform N application among treatments. Soil samples were collected at six depths and changes in SOC and total N pools were analyzed. Treatments of NTRRM and NTR sequestered more SOC and total N in the 0‐ to 5‐cm depth than CTRR. In the subsoil (5–60 cm), annual SOC sequestration was 0.01 and −0.40 Mg ha−1 yr−1 for NTRRM and NTR, respectively, while CTRR exhibited a significantly positive SOC pool trend. In the whole soil profile (0–60 cm), NTRRM, NTR, and CTRR sequestered SOC at the rates of 0.66, 0.27 and 2.24 Mg ha−1 yr−1. When manure was applied to substitute for the N lost from residue removal, the NTRRM tended to accumulate more SOC than NTR, and had similar accumulation as NTR in total N pools, grain yield, and aboveground biomass. Crop residue could be substituted by manure in this double‐crop, irrigated system. Conventional tillage, with residue removed, was suitable in soil fertility and agronomic productivity relative to NTRRM and NTR in the NCP.