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1.
Conservation agriculture (CA) based on best‐bet crop management practices may increase crop and water productivity, as well as conserve and sustain soil health and natural resources. In a 2‐year study, we assessed the effects of tillage and crop establishment (TCE) methods on productivity, profitability and soil physical properties in a rice–wheat (RW) system. The six TCE treatments were used to study the impact, which are puddled transplanted rice followed by conventionally tilled wheat (CTPR–CTW), direct‐seeded rice on the flat followed by zero‐till wheat (CTDSR–ZTW), zero‐till direct‐seeded rice with residue followed by zero‐till wheat with residue (ZTDSR+R–ZTW+R), transplanted rice after rotavator puddling followed by zero‐till wheat (RTTPR–ZTW), transplanted rice after rotavator puddling followed by rotary till wheat (RTTPR–RTW) and farmer practice rice–wheat (FP–RW). Result of the study revealed that mean rice yield was not significantly affected by different TCE methods. Wheat planted with ZTDSR+R–ZTW+R gave 30% larger grain yield than FP‐RW. Overall, among all the TCE treatments, the RW system yields and net returns were maximum under ZTDSR+R–ZTW+R. The fastest mean infiltration rate (0.10 cm hr–1) was registered in ZTDSR+R–ZTW+R plots, whereas the slowest was in FP‐RW plots (0.05 cm hr–1). Bulk density at 15–20 cm soil depth was least in ZTDSR+R–ZTW+R (1.70 Mg m–3) and greatest in FP‐RW (1.73 Mg m–3). Results from this study revealed that conventionally tilled (CT) and transplanting of rice could be successfully replaced by adoption of the profitable double ZT–RW system.  相似文献   

2.
Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha−1 total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique.  相似文献   

3.
The sustainability of rice–wheat cropping system (RWCS) is threatened by increasing labor, water, and energy crises in the region. Conservation RWCSs offers an ecofriendly alternate option. This study was aimed to evaluate the impact of sesbania brown manuring in direct‐seeded aerobic rice (DSAR) and of rice residue mulch in no‐tilled wheat (NTW) on soil health, weed dynamics and system productivity. The experiment was composed of five RWCS systems: (i) DSAR‐NTW; (ii) DSAR + sesbania brown manuring‐NTW; (iii) DSAR‐NTW + rice residue mulch; (iv) puddled transplanted flooded rice (PudTR)‐NTW; and (v) PudTR‐plow‐tilled wheat. Sesbania brown manuring in direct‐seeded rice decreased the weed density and dry biomass 41–56% and 62–75%, respectively, than the sole direct‐seeded rice crop. At rice harvest, better soil health, in terms of total nitrogen (N), soil organic carbon, soil microbial biomass carbon, and soil microbial biomass nitrogen, was noted with DSAR + sesbania brown manuring‐NTW. Rice residue mulch retention in NTW decreased weed density and dry weight by 60 and 69%, respectively, than those under NTW with no mulch. At wheat harvest, highest total N, soil organic carbon, and soil microbial biomass carbon were recorded with DSAR‐NTW + rice residue mulch, followed by DSAR + sesbania brown manuring‐NTW. Overall, NTW grown after DSAR + sesbania brown manuring produced more grain yield than PudTR‐NTW and PudTR‐plow‐tilled wheat systems. In conclusion, sesbania brown manuring in DSAR and residue mulch retention in NTW may be opted to improve soil properties, suppress weeds, and to harvest better grain yield and achieve higher system productivity in conservation RWCSs. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

4.
Changes in agricultural management strategies have received much attention in recent years with a view to increasing or maintaining the amount of carbon (C) sequestered as soil organic C (SOC). In many parts of the world, minimum or no‐till management has been promoted as a means of improving soil quality, reducing losses of erosion and potentially increasing SOC stocks. However, no‐till systems can become problematic and potentially disease‐prone, especially due to high crop residue loadings. Consequently, residue removal either by harvesting or burning off may be employed to reduce these pressures. Here, we examined the effect of crop residue removal on C storage in soil that had been under no‐till management for 20 yr. We predicted improved physical properties (i.e. lower bulk density) and greater microbial activity under the residue retention soils due to greater readily available C and nutrients derived from crop residues. In contrast, we predicted relative reductions in SOC in the no residue soils due to a lack of available residue‐derived C for microbial use. Residue removal caused a relative C loss from the soil, which was related to C input, amount of nutrient availability and microbial activity. We demonstrate the importance of maintaining crop residue cover in no‐till cropping systems for soil function and highlight the potentially deleterious effects of changing management strategy to increased residue harvesting or removal by burning.  相似文献   

5.
Conservation agriculture might have the potential to increase soil organic C content compared to conventional tillage based systems. The present study quantified soil organic carbon (SOC) and soil C derived from C3 (wheat) and C4 (maize) plant species using δ13C stable isotope. Soil with 16 y of continuous application of zero tillage (ZT) or conventional tillage (CT), monoculture (M) or rotation (R) of wheat and maize, and with (+r) and without retention (−r) in the field of crop residues were studied in the central highlands of Mexico. The highest SOC content was found in the 0-5 cm layer under ZTM and ZTR with residues retention. The soil cultivated with maize showed a higher SOC content in the 0-10 cm layer with residue retention than without residue. In the 10-20 cm layer, the highest SOC content was found in the CT treatment with residue retention. The SOC stock expressed as equivalent soil mass was greatest in the 0-20 cm layer of the ZTM (wheat and maize) and ZTR cultivated treatments with residue retention. After 16 y, the highest content of soil δ13C was found in ZTM + r and CTM + r treated soil cultivated with maize; −16.56‰ and −18.08‰ in the 0-5 cm layer, −18.41‰ and −18.02‰ in the 5-10 cm layer and −18.59‰ and −18.72‰ in the 10-20 cm layer respectively. All treatments had a higher percentages of C-C3 (derived from wheat residues or the earlier forest) than C-C4 (derived from maize residues). The highest percentages of C-C4, was found in ZTM + r and CTM + r treated soil cultivated with maize, i.e. 33.0% and 13.0% in 0-5 cm layer, 9.1% and 14.3% in the 5-10 cm layer and 5.0% and 6.8% in 10-20 cm layer, respectively. The gross SOC turnover was lower in soil with residue retention than without residues. It was found that the ZT system with residue retention and rotation with wheat is a practice with a potential to retain organic carbon in soil.  相似文献   

6.
Abstract. A 15-year field experiment investigated crop residue management practices, with crop residue removal, burning and incorporation as the main treatments and nitrogen levels as subtreatments. The effects of crop residue management practices on rice and wheat yield were measured for 11 years. Surface soil samples were taken to study nitrogen and phosphorus immobilization/adsorption and their release under laboratory conditions. The field experiment indicated that residue burning and residue removal resulted in greater grain yields of rice (5.57 and 5.53 t/ha, respectively) and wheat (4.12 and 4.02 t/ha, respectively) than residue incorporation (4.51 t/ha rice and 3.72 t/ha wheat). Laboratory experiments indicated that by the addition of crop residues nitrogen and phosphorus were converted to unavailable forms through immobilization and adsorption, respectively.
Crop residue management practices were discontinued after 13 years and wheat and maize crops were grown in sequence. There were significantly greater yields of wheat (3.57 t/ha in 1992–93 and 3.6 t/ha in 1993–94) and of maize (2.1 t/ha in 1993) in plots where the residues had previously been incorporated than where the residues were previously either removed or burned. This is attributed to release of nitrogen and phosphorus from the incorporated residues.  相似文献   

7.
The long-term crop residue retention coupled with external nutrient inputs are crucial for maintaining soil phosphorus (P) and soil organic carbon (SOC) in Vertisols of Central India. A study was conducted to evaluate the long-term effect of three wheat residue management practices (residue burning, incorporation, and surface retention) in combination with three supplementary nutrient inputs (SNI) [control, fertilizer, and farmyard manure (FYM)] on stratification of P and SOC in the soybean–wheat system in Vertisol. The wheat residue either incorporated or retained on the soil surface increased the availability of P and SOC content as compared to the common practices of residue burning. Residue retention or incorporation increased stratification of P and soil organic carbon over the residue burning. Irrespective of the nutrient treatments, greater stratification ratio of SOC and P were registered under wheat residue incorporation or retention compared to residue burning. It is evident from the study that wheat residue incorporation or retention plus addition of FYM could be an effective strategy for increasing the soil fertility in a soybean–wheat system of Vertisols of Central India.  相似文献   

8.
Agricultural productivity relies on a wide range of ecosystem services provided by the soil biota. Sustainable management practices, such as tillage and residue management, can influence structure and function of the soil microbiota, with direct consequences for the associated ecosystem services. Although there is increasing evidence that different tillage regimes alter the soil biological indices, we only have a limited understanding of their temporal changes in a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system. We evaluated the effects of combinations of tillage, crop residue management and green manuring on soil biological indicators after 5 years of the practising rice–wheat system (RWS). Four main plot treatments in rice included the following: (a) PTRW0, puddled transplanted rice with no wheat straw retained; (b) PTRW25, puddled transplanted rice with 25% anchored wheat stubbles retained; (c) PTRW0 + Sesbania aculeate L. green manure (GM); and (d) PTRW25+GM, puddled transplanted rice with 25% anchored wheat stubbles retained+ GM. There were three subplot treatments in the subsequent wheat crop: (a) CTWR0, conventional tillage wheat with rice residue removed; (b) ZTWR0, zero tillage wheat with rice residue removed; and (c) ZTWR100, ZTW with 100% rice residue retained as mulch. The PTRW25+GM treatment, followed by ZTWR100, significantly increased soil microbial biomass carbon, basal soil respiration, microbial quotient and mineralization quotient measured during wheat-growing season. These biological indicators were higher at vigorous vegetative wheat growth stage than at flowering stage and decreased at maturity. The principal component analysis of the assayed variables showed that all the variables significantly contributed to the variability in parameters examined and were more related to maximum tillering stage of wheat growth than to maturity or at sowing of wheat. Three highly effective biological indicators were microbial biomass carbon, microbial quotient and mineralization quotient, which responded significantly to changes in tillage and residue management practices in the RWS. We conclude that crop residues and green manure have significant to improve soil biochemical processes by improving soil organic carbon and soil biological indicators in rice–wheat cropping system.  相似文献   

9.
Field experiments were conducted on a river deposit during 1983–1984 and 1984–1985 in order to study the effect of different soil management practices, such as zero tillage with surface-applied crop residue mulch at a rate of 10 t ha−1 (ZT+M), conventional tillage (CT), CT+ surface-applied crop residue mulch at a rate of 10 t ha−1 (CT + M), CT+crop residue incorporation at a rate of 10 t ha−1 (CT + SI), CT + farmyard manure incorporation at a rate of 10 t ha−1 (CT + FYM), on soil hydro-thermal regime root growth, nutrient uptake and dry matter yield of winter wheat (Triticum aestivum L.). The soils of the site are classified as Entisol, Typic Psammaquent with pH 6.0, cation exchange capacity 10 c mol (p+) per kg in the surface (0–0.3 m) depth. In the CT + M and CT + FYM treatments, higher water retention was observed compared to CI. The minimum soil temperature was also raised by 3°C under CT + M to CT at 0.1-m depth. CT + M and CT + FYM had significantly higher root mass density compared with other treatments at all stages of crop growth. The nitrogen (N) uptake under these two treatments was also significantly higher compared to CT. Under CT+M, plants did not suffer from N stress compared to other treatments. Phosphorus (P) uptake (except at tillering) and potassium (K) uptake under CT+M and CT + FYM were significantly higher than for all the other treatments. Treatments ZT+M and CT+SI behave simply to CT in terms of hydro-thermal regime, root growth, nutrient uptake and dry matter yield. The grain yield under CT+M and CT+FYM during 1983–1984 and 1984–1985 was significantly higher than that under all the other treatments.  相似文献   

10.
Soil quality in rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping systems is governed primarily by the tillage practices used to fulfill the contrasting soil physical and hydrological requirements of the two crops. The objective of this study was to develop a soil quality index (SQI) based on bulk density (BD), penetration resistance (PR), water stable aggregates (WSA) and soil organic matter (OM) to evaluate this important cropping system on a Vertisol in India. Regression analysis between crop yield and SQI values for various tillage and crop residue management treatments indicated SQI values of 0.84–0.92, 0.88–0.93 and 0.86–0.92 were optimum for rice, wheat and the combined system (rice + wheat), respectively. The maximum yields for rice and wheat were 5806 and 1825 kg ha−1 occurred at SQI values of 0.85 and 0.99, respectively. Using zero tillage (ZT) for wheat had a positive effect on soil quality regardless of the treatments used for rice. Regression analyses to predict sustainability of the various tillage and crop residue treatments showed that as puddling intensity for rice increased, sustainability without returning crop residues decreased from 6 to 1 years. When residue was returned, the time for sustainable productivity increased from 6 to 15 years for direct seeded rice, 5 to 11 years with low-intensity puddling (P1) and 1 to 8 years for high-intensity (P2) puddling. For sustainability and productivity, the best practice for this or similar Vertisols in India would be direct seeding of rice with conventional tillage and residues returned.  相似文献   

11.
No‐till (NT) farming can restore the soil organic carbon (SOC) pool of agricultural soils, but the SOC pool size and retention rate can vary with soil type and duration of NT. Therefore, the objectives of this study were to determine the effects of NT and soil drainage characteristics on SOC accumulation across a series of NT fields on Alfisols in Ohio, USA. Sites under NT for 9 (NT9), 13 (NT13), 36 (NT36), 48 (NT48) and 49 (NT49) years were selected for the study. Soil was somewhat poorly drained at the NT48 site but moderately well drained at the other sites. The NT48 and NT49 on‐station sites were under continuous corn (Zea mays), while the other sites were farmers' fields in a corn–soybean (Glycine max) rotation. At each location, the SOC pool (0–30 cm) in the NT field was compared to that of an adjacent plough‐till (PT) and woodlot (WL). At the NT36, NT48 and NT49 sites, the retention rate of corn‐derived C was determined using stable C isotope (13C) techniques. In the 0‐ to 10‐cm soil layer, SOC concentration was significantly larger under NT than PT, but a tillage effect was rarely detected below that depth. Across sites, the SOC pool in that layer averaged 36.4, 20 and 40.8 Mg C/ha at the NT, PT and WL sites, respectively. For the 0‐ to 30‐cm layer, the SOC pool for NT (83.4 Mg C/ha) was still 57% greater than under PT. However, there was no consistent trend in the SOC pool with NT duration probably due to the legacy of past management practices and SOC content differences that may have existed among the study sites prior to their conversion to NT. The retention rate of corn‐derived C was 524, 263 and 203 kg C/ha/yr at the NT36, NT48 and NT49 sites. In contrast, the retention rate of corn‐C under PT averaged 25 and 153 kg C/ha/yr at the NT49 (moderately well‐drained) and NT48 (somewhat poorly drained) sites, respectively. The conversion from PT to NT resulted in greater retention of corn‐derived C. Thus, adoption of NT would be beneficial to SOC sequestration in agricultural soils of the region.  相似文献   

12.
Long‐term no‐tillage management and crop residue amendments to soil were identified as an effective measure to increase soil organic carbon (SOC). The SOC content, SOC stock (SOCs), soil carbon sequestration rate (CSR), and carbon pool management index (CPMI) were measured. A stable isotopic approach was used to evaluate the contributions of wheat and maize residues to SOC at a long‐term experimental site. We hypothesized that under no‐tillage conditions, straw retention quantity would affect soil carbon sequestration differently in surface and deep soil, and the contribution of C3 and C4 crops to soil carbon sequestration would be different. This study involved four maize straw returning treatments, which included no maize straw returning (NT‐0), 0.5 m (from the soil surface) maize straw returning (NT‐0.5), 1 m maize straw returning (NT‐1), and whole maize straw returning (NT‐W). The results showed that in the 0–20 cm soil layer, the SOC content, SOCs, CSR and CPMI of the NT‐W were highest after 14 years of no‐tillage management, and there were obvious differences among the four treatments. However, the SOC, SOCs, and CSR of the NT‐0.5 and NT‐W were the highest and lowest in 20–100 cm, respectively. The value of δ13C showed an obviously vertical variability that ranged from –22.01‰ (NT‐1) in the 0–20 cm layer to –18.27‰ (NT‐0.5) in the 60–80 cm layer, with enriched δ13C in the 60–80 cm (NT‐0.5 and NT‐1) and 80–100 cm (NT‐0 and NT‐W) layers. The contributions of the wheat and maize‐derived SOC of the NT‐0.5, NT‐1 and NT‐W increased by 11.4, 29.5 and 56.3% and by 10.7, 15.1 and 40.1%, relative to those in the NT‐0 treatment in the 0–20 cm soil layer, respectively. In conclusion, there was no apparent difference in total SOC sequestration between the NT‐0.5, NT‐1, and NT‐W treatments in the 0–100 cm soil layer. The contribution of wheat‐derived SOC was higher than that of maize‐derived SOC.  相似文献   

13.
施氮水平对黄土旱塬区小麦产量和土壤有机碳、氮的影响   总被引：13，自引：4，他引：9  
施用氮肥是雨养农业区提高作物产量和土壤有机碳（SOC）、氮[TSN（Total soil N）]含量的重要养分管理措施。利用长期田间试验（1984～2007）,定量评价了常规耕作条件下5个施氮水平N 0（N0）、45（N45）、90（N90）、135（N135）和180（N180）kg/hm2处理下,小麦子粒产量、SOC、TSN和氮肥利用效率的变化。研究了施氮水平对黄土旱塬区旱地小麦产量、SOC和TSN积累的影响。结果表明,1984～2007年期间,N0、N45、N90、N135和N180处理小麦产量的平均值依次为1.2、2.4、2.9、3.2和3.4 t/hm2;N0处理的小麦产量随试验年限而降低,年降低幅度达67 kg/hm2（P0.001）;但增施氮肥后降低趋势得到显著控制,当施氮水平提高到N 90 kg/hm2时,产量随年限呈现出缓慢升高的趋势。随着施氮水平的提高,地上部氮肥利用率由40%（N45处理）降低到28%（N180）。不同施氮水平条件下,SOC含量随年限呈缓慢升高趋势。23年后（2007年）,N0、N45、N90、N135和N180处理下,0—20 cm土层SOC储量依次为16.9、18.2、18.7、19.0和19.1 t/hm2;TSN储量依次为2.03、2.16 、2.24 、2.34和2.37 t/hm2。施氮水平与产量呈显著的抛物线关系（R2＝0.993）。产量与SOC存在着极显著的线性相关关系（R2=0.997）。增施N 1 kg/hm2,小麦产量可提高29 kg/hm2,SOC提高1.2 kg/hm2,TSN提高0.13 kg/hm2。根茬还田量的增加是导致黄土旱塬区SOC和TSN提高的主要因素。  相似文献   

14.
Residue retention and reduced tillage are both conservation agricultural practices that may enhance soil organic carbon (SOC) stabilization in soil. We evaluated the long‐term effects of no‐till (NT) and stover retention from maize on SOC dynamics in a Rayne silt loam Typic Hapludults in Ohio. The six treatments consisted of retaining 0, 25, 50, 75, 100 and 200% of maize residues on each 3 × 3 m plot from the crop of previous year. Soil samples were obtained after 9 yrs of establishing the experiment. The whole soil (0–10 and 10–20 cm of soil depths) samples under different treatments were analysed for total C, total N, recalcitrant C (NaOCl treated sample) and 13C isotopic abundance (0–10 cm soil depth). Complete removal of stover for a period of 9 yrs significantly (P < 0.01) decreased soil C content (15.5 g/kg), whereas 200% of stover retention had the maximum soil C concentration (23.1 g/kg). Relative distribution of C for all the treatments in different fractions comprised of 55–58% as labile and 42–45% as recalcitrant. Retention of residue did not significantly affect total C and N concentration in 10–20 cm depth. 13C isotopic signature data indicated that C4‐C (maize‐derived C) was the dominant fraction of C in the top 0–10 cm of soil layer under NT with maize‐derived C accounting for as high as 80% of the total SOC concentration. Contribution of C4‐C or maize‐derived C was 71–84% in recalcitrant fraction in different residue retained plots. Residue management is imperative to increase SOC concentrations and long‐term agro‐ecosystem necessitates residue retention for stabilizing C in light‐textured soils.  相似文献   

15.
The maintenance and accumulation of soil organic carbon (SOC) in agricultural systems is critical to food security and climate change, but information about the dynamic trend and efficiency of SOC sequestration is still limited, particularly under long‐term fertilizations. In a typical Purpli‐Udic Cambosols soil under subtropical monsoon climate in southwestern China this study thus estimated the dynamic, trend and efficiency of SOC sequestration after 22‐year (1991–2013) long‐term inorganic and/or organic fertilizations. Nine fertilizations under a rice–wheat system were examined: control (no fertilization), N, NP, NK, PK, NPK, NPKM (NPK plus manure), NPKS (NPK plus straw), and 1.5NPKS (150% NPK plus straw). Averagely, after 22‐years SOC contents were significantly increased by 4.2–25.3% and 10.2–32.5% under these fertilizations than under control conditions with the greatest increase under NPKS. The simulation of SOC dynamic change with an exponential growth equation to maximum over the whole fertilization period predicted the SOC level in a steady state as 18.1 g kg?1 for NPKS, 17.4 g kg?1 for 1.5NPKS, and 14.5–14.9 g kg?1 for NK, NP, NPK, and NPKM, respectively. Either inorganic, organic or their combined fertilization significantly increased crop productivity and C inputs that were incorporated into soil ranging from 0.91 to 4.63 t (ha · y)?1. The C sequestration efficiency was lower under NPKM, NPKS, and 1.5NPKS (13.2%, 9.0%, and 10.1%) than under NP and NPK (17.0% and 14.4%). The increase of SOC was asymptotical to a maximum with increasing C inputs that were variedly enhanced by different fertilizations, indicating an existence of SOC saturation and a declined marginal efficiency of SOC sequestration. Taken all these results together, the combined NPK plus straw return is a suitable fertilizer management strategy to simultaneously achieve high crop productivity and soil C sequestration potential particularly in crop rotation systems.  相似文献   

16.
Climate, soil physical–chemical characteristics, land management, and carbon (C) input from crop residues greatly affect soil organic carbon (SOC) sequestration. According to the concept of SOC saturation, the ability of SOC to increase with C input decreases as SOC increases and approaches a SOC saturation level. In a 12‐year experiment, six semi‐arid cropping systems characterized by different rates of C input to soil were compared for ability to sequester SOC, SOC saturation level, and the time necessary to reach the SOC saturation level. SOC stocks, soil aggregate sizes, and C inputs were measured in durum wheat monocropping with (Ws) and without (W) return of aboveground residue to the soil and in the following cropping systems without return of aboveground residue to soil: durum wheat/fallow (Wfall), durum wheat/berseem clover, durum wheat/barley/faba bean, and durum wheat/Hedysarum coronarium. The C sequestration rate and SOC content were lowest in Wfall plots but did not differ among the other cropping systems. The C sequestration rate ranged from 0.47 Mg C ha−1 y−1 in Ws plots to 0.66 Mg C ha−1 y−1 in W plots but was negative (−0.06 Mg C ha−1 y−1) in Wfall plots. Increases in SOC were related to C input up to a SOC saturation value; over this value, further C inputs did not lead to SOC increase. Across all cropping systems, the C saturation value for the experimental soil was 57.7 Mg ha−1, which was reached with a cumulative C input of 15 Mg ha−1. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

17.
Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.  相似文献   

18.
An experiment was carried out during the year 1990–91 and 1991–92 at the University farm, Mohanpur in order to study the response of manurial residue to wheat crop at different doses of fertilizer under rice‐wheat cropping sequence. Incorporation of farm yard manure @ 10 t/ha to winter paddy showed significant effect on succeeding crop, wheat as compared to only fertilizer use in both the crops. Grain yield, and number of effective tillers/m2 of wheat were significantly influenced by manurial residue and attained their highest values at 100 per cent recommended dose of fertilizer with moderate soil health. Manurial residue showed higher rate of increment in grain yield of wheat at 75 per cent dose of fertilizer but leaving the soil with poor fertility condition.  相似文献   

19.
In recent years conventional production technologies in the rice–wheat (RW) system have been leading to deterioration of soil health and declining farm profitability due to high inputs of water and labour. Conservation agriculture (CA)-based resource-conserving technologies (RCTs) vis-à-vis zero-till (ZT), raised-bed planting and direct-seeded rice (DSR) have shown promise as alternatives to conventional production technologies to overcome these problems. The integration of CA-based RCTs with precision agriculture (PA)-based technologies in a systems perspective could provide a better option for sustainable RW production systems. In this study we attempted to evaluate conservation and precision agriculture (CPA)-based RCTs as a double-ZT system integrated with laser-assisted precision land leveling (PLL) in the RW system. A field experiment was conducted in the western IGP for 2 years to evaluate various tillage and crop establishment methods under PLL and traditional land leveling (TLL) practices to improve water productivity, economic profitability and soil physical quality. Irrespective of tillage and crop establishment methods (TCE), PLL improved RW system productivity by 7.4% in year 2 as compared to traditional land leveling. Total irrigation water savings under PLL versus TLL were 12–14% in rice and 10–13% in wheat. PLL improved RW system profitability by US$113 ha−1 (year 1) to $175 ha−1 (year 2). Yields were higher in conventionally transplanted rice followed by direct-drill-seeded rice after ZT. In wheat, yields were higher in ZT when followed by DSR than in the conventional-till (CT) system. RW system productivity under double ZT was equivalent to that of the conventional method. Among different TCE, conventional puddled-transplanted rice-CT wheat required 12–33% more water than other TCE techniques. Compared with CT systems, double ZT consumed 12–20% less water with almost equal system productivity and demonstrated higher water productivity. The CT system had higher bulk density and penetration resistance in 10–15 and 15–20 cm soil layers due to compaction caused by the repeated wet tillage in rice. The steady-state infiltration rate and soil aggregation (>0.25 mm) were higher under permanent beds and double ZT and lower in the CT system. Under CT, soil aggregation was static across seasons, whereas it improved under double no-till and permanent beds. Similarly, mean weight diameter of aggregates was higher under double ZT and permanent beds and increased over time. The study reveals that to sustain the RW system, CPA-based RCTs could be more viable options: however, the long-term effects of these alternative technologies need to be studied under varying agro-ecologies.  相似文献   

20.
A field experiment was conducted for 3 crop years (July‐June) at the Indian Agricultural Research Institute, New Delhi to study the effects of Sesbania and cowpea green manuring (GM) and incorporation of mungbean residues after harvesting grain, Leucaena loppings, FYM and wheat straw incorporation before planting rice and application of 0,40,80 and 120 kg N ha?1 to rice on the soil organic carbon (SOC), alkaline permanganate oxidizable N (APO‐N), 0.5 M sodium bicarbonate extractable P (SBC‐P) and 1N ammonium acetate exchangeable K (AAE‐K) in surface 0–15 cm soil after the harvest of rice and wheat grown in sequence. Green manuring and addition of organic residues prevented the decline in SOC. On the other hand addition of N fertilizer tended to decrease SOC after rice harvest. On the contrary application of green manures, organic residues, FYM and fertilizer N increased APO‐N, which indicates the benefit of these treatments to a more labile soil organic N pool. Also application of green manures, organic residues, FYM and fertilizer N increased SBC‐P. Not much change was observed in AAE‐K by the treatments applied.  相似文献   

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