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1.
Organic farming is considered an effective means of reducing nitrogen losses compared with more intensive conventional farming systems. However, under certain conditions, organic farming may also be susceptible to large nitrogen (N) losses. This is especially the case for organic dairy farms on sandy soils that use grazed grass–clover in rotation with cereals. A study was conducted on two commercial organic farms on sand and loamy sand soils in Denmark. On each farm, a 3‐year‐old grass–clover field was selected. Half of the field was ploughed the first year and the other half was ploughed the following year. Spring barley (Hordeum vulgare L.) was sown after ploughing in spring. Measurements showed moderate N leaching during the pasture period (9–64 kg N ha?1 year?1) but large amounts of leaching in the first (63–216 kg N ha?1) and second (61–235 kg N ha?1) year after ploughing. There was a small yield response to manure application on the sandy soil in both the first and second year after ploughing. To investigate the underlying processes affecting the residual effects of pasture and N leaching, the dynamic whole farm model farm assessment tool (FASSET) was used to simulate the treatments on both farms. The simulations agreed with the observed barley N‐uptake. However, for the sandy soil, the simulation of nitrate leaching and mineral nitrogen in the soil deviated considerably from the measurements. Three scenarios with changes in model parameters were constructed to investigate this discrepancy. These scenarios suggested that the organic matter turnover model should include an intermediate pool with a half‐life of about 2–3 years. There might also be a need to include effects of soil disturbance (tillage) on the soil organic matter turnover.  相似文献   

2.
The economic benefits of organic agriculture and its wide adoption are well documented, but the impact of that practice on soil C dynamics in irrigated croplands of semi‐arid regions is less well understood. In manure‐based organic production systems, land applications of animal wastes not only provide nutrients but could also contribute to soil carbon sequestration. A study was conducted in irrigated cotton (Gossypium arboreum L) agro‐ecosystems of New Mexico (USA) under conventional (CONV; 100 kg N/ha as urea and NH4NO3) and organic farming practices (OF for 3–9 yr; 50 Mg dry manure/ha) to assess the effect of OF on soil C stocks (organic, inorganic) and biochemical indices [microbial biomass C (MBC); respiration; metabolic quotient (qCO2)]. In the plough layer (0–30 cm), soil organic carbon (SOC) stocks tended to be higher (although not statistically) under OF (35.9 Mg C/ha) than CONV (33.5 Mg C/ha). However, when the entire 100‐cm soil profile was considered, the total SOC under CONV exceeded that under OF by 39.8 Mg C/ha, but this may be influenced by other factors. Accounting for 52% of the total C stock, inorganic C was significantly higher under CONV than OF and was positively correlated with soil respiration and the H/C ratio of soil organic matter. While OF duration had no consistent effect on soil biochemical properties, MBC was significantly higher (1.5 times) and the qCO2 (3–6 times) was lower in the organically fertilized soils than under CONV. These results suggest the development, under OF, of a soil microbial community that is larger and processes added C substrates more efficiently compared with the community present in CONV practices.  相似文献   

3.
Under semiarid climatic conditions, intensive tillage increases soil organic matter losses, reduces soil quality, and contributes to climate change due to increased CO2 emissions. There is a need for an agricultural management increasing soil organic matter. This paper presents the organic carbon (OC) and nitrogen (N) stocks, C:N ratio and stratification ratios (SRs) of these properties for olive groves soils under long‐term organic farming (OF), and conventional tillage (CT) in Los Pedroches valley, southern Spain. The results show that OF increased C and N stocks. The soil organic carbon (SOC) stock was 73·6 Mg ha−1 in OF and 54·4 Mg ha−1 in CT; and the total nitrogen (TN) stock was 7·1 Mg ha−1 and 5·8 Mg ha−1 for OF and CT, respectively. In the surface horizon (A: 0–16·9 cm in OF and Ap: 0–21·8 cm in CT) and Bw horizon (16·9–49·6 cm in OF and 21·8–56 cm in CT), SOC and TN concentrations and C:N ratios were higher in OF than in CT. Soil properties stratification in depth, expressed as a ratio, indicates the soil quality under different soil management systems. The SR of SOC ranged from 2·2 to 3·1 in OF and from 2·1 to 2·2 in CT. However, only SR2 (defined by Ap‐A/C) showed significant differences between CT and OF. The SR of TN showed similar trends to that of the SR of SOC. Organic farming contributes to a better soil quality and to increased carbon sequestration. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

4.
Conventional agricultural practices that use excessive chemical fertilizers and pesticides come at a great price with respect to soil health, a key component to achieve agricultural sustainability. Organic farming could serve as an alternative agricultural system and solve the problems associated with the usage of agro‐chemicals by sustainable use of soil resources. A study was carried out to evaluate the impact of organic vs . conventional cultivations of basmati rice on soil health during Kharif (rainy) season of 2011 at Kaithal district of Haryana, India, under farmers' participatory mode. Long‐term application of organic residues in certified organic farms was found to improve physical, chemical, and biological indicators of soil health. Greater organic matter buildup as indicated by higher soil organic carbon content in organic fields was critical to increase soil aggregate stability by increasing water holding capacity and reducing bulk density. Proper supplementation of nutrients (both major and micro nutrients) through organic residue addition favored biologically available nutrients in organic systems. Further, the prevalence of organic substrates stimulated soil microorganisms to produce enzymes responsible for the conversion of unavailable nutrients to plant available forms. Most importantly, a closer look at the relationship between physicochemical and biological indicators of soil health evidenced the significance of organic matter to enzyme activities suggesting enhanced nutrient cycling in systems receiving organic amendments. Enzyme activities were very sensitive to short‐term (one growing season) effects of organic vs . conventional nutrient management. Soil chemical indicators (organic matter and nutrient contents) were also changed in the short‐term, but the response was secondary to the biochemical indicators. Taken together, this study indicates that organic farming practices foster biotic and abiotic interactions in the soil which may facilitate in moving towards a sustainable food future.  相似文献   

5.
The importance of the soil humus content is indisputable. Soil humus plays an important role in preserving soil fertility and exerts great influence on plant production and yield potential. However, proofing that management‐related changes in the stock of soil organic matter (SOM) have taken place against the background of spatial and temporal variation is a difficult task. In most cases, sampling over a long period of time is needed to verify these changes. Alternatively, potential changes in the SOM stock can be estimated using humus balancing models, which help to identify the need for humus reproduction on a farm. In general, a humus balance is the difference between the humus demand of cultivated crops and humus supply through crops and organic fertilizers. In this study, the ‘Dynamic Humus Unit Method' within the modelling program REPRO was applied to calculate the humus balance for 29 model‐farms that are representative of most of the agricultural production in Austria. Each model‐farm represents a specific production type (PT) and farming system in a defined region or main production area (MPA). This approach gives an overview of the humus balances at a large scale and allows a general trend in Austria to be estimated. Besides differing between conventional and organic farming systems, specific site conditions can also be selected in the model. The constructed model‐farms belong to different PTs such as “forage production”, “cash crops”, “refinement”, and “permanent crops”. The PT “permanent crops” refers to the cultivation of wine. The cropping system of each PT was analyzed in detail, while livestock keeping was considered only when applicable. Positive humus balances were found for all PTs except for permanent crops. The results ranged from –122 to 890 kg C ha?1 y?1. Regions and farm structure, e.g., forage production compared to cash crop, were found to have a greater influence than the kind of farming system (i.e., organic vs. conventional farming). Comparing the different PTs, forage production had the highest positive humus balances (219 to 890 kg C ha?1 y?1), followed by cash crop (24 to 239 kg C ha?1 y?1), refinement (–64 to 402 kg C ha?1 y?1) and permanent crops (–122 to –38 kg C ha?1 y?1). Regarding the farming system, organic farming led to more humus accumulation than conventional farming due to a higher share of fodder legumes and catch crops and more diverse crop rotations. The results were within the range of available empirical data on SOM change, and it was therefore concluded that the results are reasonable. In general, humus reproduction can be regarded as sufficient for agricultural production.  相似文献   

6.
Soil properties and agricultural practices take a joint effect on the communities of soil bacteria. The aim of the present study was to survey Alphaproteobacterial communities as possible indicators of soil quality considering clay, loamy and sandy soils under conventional and organic farming. Alphaproteobacteria community composition were analysed by 16S rRNA gene with nested-PCR (polymerase chain reaction) and denaturing gradient gelelectrophoresis (DGGE). Sequencing of partial 16S rRNA gene from the DGGE bands were performed. Conventional and organic farming resulted in significant differences in chemical properties of soils. According to the results community fingerprints were separated into groups depending on soil types and farming systems. This separation can be attributed mostly to soil pH, AL-P2O5,-K2O. The analysed sequences were identified as soil bacteria which could play the main role in nitrogen fixing, mineralisation and denitrification. The highest diversity index was revealed from the organic farming at sandy texture site, where mainly Mesorhizobium sp. and Rhizobium sp. were detected. The soil type and actual crop could have a stronger impact on the soil bacterial composition than the management.  相似文献   

7.
Agricultural intensification has been vital for meeting global food demand but has caused environmental degradation. This has disrupted the ability of soil to provide vital ecosystem services. Organic farming is often thought to conserve and utilise soil ecosystem services, and thus be a more sustainable method of food production than conventional farming. However, evidence for this is equivocal, and little is known of the potential trade-offs between soil functions, which can be classified as supporting and provisioning ecosystem services, in conventional and organic systems. In addition, few studies have simultaneously examined how surrounding landscape heterogeneity affects soil functions in agriculture. In this study we investigated the effects of farming method (conventional versus organic) and landscape heterogeneity (100 m, 500 m and 1000 m radius) on indicators of soil ecosystem services: soil organic carbon (SOC), total nitrogen (TN), water holding capacity (WHC) and plant-available phosphorous (P) (measures of carbon storage and nutrient retention); net N mineralisation and microbial community composition and biomass (nutrient cycling); and crop yield. We found no effect of landscape heterogeneity, and no differences in any of the measured soil and microbial variables between conventional and organic farms, apart from net N mineralisation, which was higher in organic farms. However, conventional farms had significantly greater yield than organic farms, and there was no apparent trade-off between increasing yield and the level of supporting ecosystem services. The organic farms in this study appear to have been intensively managed, with a straight substitution of organic inputs for chemicals, but little other effort to enhance soil fertility. For example, the organic farms applied large quantities of manure compared with conventional farms but conducted mechanical weeding (harrowing), whereas conventional farms applied herbicides. This repeated soil disturbance may cause rapid organic matter mineralisation and undermine the ability of these organic farms to retain carbon and nitrogen. The terms ‘organic’ and ‘conventional’ agriculture both cover a wide variety of farming methods, some of which enhance or deplete ecosystem services more than others. To develop truly sustainable methods of agriculture, research should focus on the effects of specific farming practices, rather than the labels ‘conventional’ and ‘organic’.  相似文献   

8.
ABSTRACT

Organic amendments in the soil perform better than synthetic fertilizers in regards to soil fertility and sustainable crop productivity. Experiments were conducted to compare the effects of organic and synthetic fertilizers on soil fertility and wheat (Triticum aestivum L.) productivity. Soil fertility and protein contents of wheat grains (13.2% and 13.3% during 2005–06 and 2006–07, respectively) were improved by organic amendments. However, synthetic fertilizer (at the rate of 150, 100, and 60 kg ha?1 N, P2O5, and K2O, respectively) applications resulted in the maximum grain yield (4.05 and 4.46 t ha?1 during 2005–06 and 2006–07, respectively). The observed and simulated soil organic carbon (SOC) reasonably agreed during RothC model validation (R 2 = 0.99). Economic analysis showed the maximum net profit and relative increase in income ($729 US ha?1 and 309%, respectively) from inorganic treatment. Application of synthetic fertilizers increased grain yield and farm profit while organic manure enhanced grain quality. The RothC model had potential for determining the SOC in organic farming under arid environment.  相似文献   

9.
Purpose

Although litter decomposition and nutrient release patterns have been studied in cocoa agroforestry systems in general, studies focusing on organic and conventional cocoa systems are lacking which is critical as organic farms are particularly dependent on nutrient returns from decomposing litter.

Materials and methods

Dynamics in leaf litter decomposition and the mineralisation of macro- and micro-nutrients in organic and conventional cocoa agroforestry systems were studied using the litterbag technique for 12 months.

Results

The average monthly mass loss was more than two times higher on organic farms (9.2–14.4 g month?1) compared to conventional farms (4.2–7.3 g month?1) in the first five months. The annual rate of decomposition (k) was higher on organic farms (1.9) compared to conventional systems (1.4). The time required for 50% (t50) and 99% (t99) decomposition of leaf litter was both lower on organic farms (t50?=?0.4 years, t99?=?2.6 years) than conventional farms (t50?=?0.5 years, t99?=?3.5 years). The estimated k values for macro- and micro-nutrients on organic cocoa systems ranged from 2.3 for calcium to 4.5 for potassium compared to 1.6 (Ca) to 2.8 (K) on conventional farms. The k values of all nutrients (except nitrogen and phosphorus) were significantly greater on organic farms than conventional systems. The estimated k values for both litter decomposition and nutrient mineralisation correlated with soil pH and moisture content, but not initial litter chemistry.

Conclusions

Organic management of smallholder cocoa agroforestry systems enhanced leaf litter decomposition and nutrient mineralisation through improved soil conditions. Thus, organic management of cocoa agroforestry systems may contribute to sustainable cocoa production in smallholder systems through enhanced nutrient return from litter decomposition.

  相似文献   

10.
Some organic arable and vegetable farms in the Netherlands use cm-precise guidance of machinery to restrict wheel traffic to fixed traffic lanes and to achieve non-trafficked cropping zones with optimized soil structure in between the lanes. Contrary to controlled traffic farming (CTF) the traffic lanes are not yet used for harvesting and primary tillage. Therefore, the system is called a seasonal-controlled traffic farming (SCTF) system. A field experiment was conducted on an organic vegetable farm to reveal soil, crop and emission responses of SCTF with traffic lanes at 3.15-m centres compared with conventional random traffic farming (RTF) using low ground pressures in spring from 2002 till 2005. The traffic systems were investigated in the crops green pea (Pisum sativum L.), spinach (Spinacea oleracea L.), onions (Allium cepa L.) and carrots (Daucus carota L.). Compared with RTF, the topsoil structure in the SCTF system improved for the crops sown on the flat but not for carrot grown on ridges. Crop yields increased significantly in green pea, spinach and planted onion sets but not in carrot and direct-sown onion. The available N-min at the end of the cropping period was not different between systems and, therefore, leaching losses in winter are expected to be the same. SCTF resulted in a significant reduction of N2O emissions (by 20–50% compared to RTF). For CH4, application of the SCTF system resulted in increased CH4 uptake (by a factor 5–20) compared to the RTF system in three of the four measured fields. At the fourth field, lower (but not significant) CH4 emissions (by a factor 4) were measured in the SCTF system compared to RTF. Effects of SCTF on timeliness and on the economic feasibility are discussed.  相似文献   

11.
The effects of conventional and biological farming systems on soil P dynamics were studied by measuring some microbiological parameters after 13 years of different cropping systems. The treatments included control, biodynamic, bio-organic, and conventional plots and a mineral fertilizer treatment. The farming systems differed mainly in the form and quantity of nutrients applied and in the plant protection strategies. The results of a sequential fractionation procedure showed that irrespective of the form of P applied, neither 0.5 M NaHCO inf3 sup- nor 0.1 M NaOH-extractable organic P, but only the inorganic fractions, were affected. The residual organic P, not extracted by NaHCO3 or NaOH was increased in the biodynamic and bio-organic plots. The soil microbial biomass (ATP content) and the activity of acid phosphatase were also higher in both biologically managed systems. These results were attributed to the higher quantity of organic C and organic P applied in these systems, but also to the absence of or severe reduction in chemical plant protection. The relationship between acid soil phosphatase and residual organic P was interpreted as an indication that this fraction might be involved in short-term transformations. The measurement of the intensity, quantity, and capacity factors of available soil P using the 32P isotopic exchange kinetic method showed that P could not be the factor limiting crop yield in the biological farming systems. The kinetic parameters describing the ability of P ions to leave the soil solid phase, deduced from isotopic exchange, were significantly higher for the biodynamic treatment than for all other treatments. This result, showing a modification of chemical bonds between P ions and the soil matrix, was explained by the higher Ca and organic matter contents in this system.  相似文献   

12.
Tillage modifies soil structure and has been suggested as a practice to improve physical, hydrological and chemical properties of compacted soils. But little is known about effect of long‐term tillage on physicochemical soil properties and crop yield on sodic soils in India. Our objective was to investigate the effect of different tillage regimes on crop yield (wheat and paddy rice) and physicochemical properties of sodic soils. Two sodic sites under conventional tillage for 5 (5‐YT; 5‐year tillage) and 9 (9‐YT; 9‐year tillage) years were selected for this study. Changes in crop yield and physicochemical soil properties were compared with a control, sodic land without any till history, that is, 0‐year tillage/untilled (0‐YT). Five replicated samples at 0‐ to 10‐cm and 10‐ to 20‐cm soils depths were analysed from each site. In the top, 0‐ to 10‐cm soil depth 5‐YT and 9‐YT sites had higher particle density (Pd), porosity, water holding capacity, hydraulic conductivity, organic carbon, total nitrogen (Nt), available nitrogen (Navail), phosphorus (Pavail) and exchangeable calcium (Exch. Ca++) than 0‐YT, whereas bulk density (Bd), C : N ratio and CaCO3 were significantly lower. Bd, pH, EC and CaCO3 increased significantly with depth in all the lands, whereas Pd, porosity, water holding capacity, hydraulic conductivity, organic carbon, Nt, Navail, Pavail and Exch. Ca++ decreased. We conclude that continuous tillage and cropping can be useful for physical and chemical restoration of sodic soils. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

13.
ABSTRACT

Understanding how plants use of various nitrogen (N) sources is important for improving plant N use efficiency in organic farming systems. This study investigated the effects of farming management practices (organic and conventional) on pakchoi short-term uptake of glycine (Gly), nitrate (NO3 ?) and ammonium (NH4 +) under two N level conditions. Results showed that plant N uptake rates and N contributions from the three N forms in the low N (0.15 μg N g?1 dry soil) treatment did not significantly differ between the organic and conventional soils, except the significantly greater Gly contribution in organic soil at 24 h after tracer addition. Under high N (15 μg N g?1 dry soil) conditions, the N uptake rates, uptake efficiencies, and N contributions of Gly and NH4 +-N were significantly greater in pakchoi cultivated in the organic soil compared to conventional soil, whereas the N uptake rates and N contributions from NO3 –-N decreased in pakchoi cultivated in the organic soil. The greater Gly-N uptake in plants grown in high-N treated organic soil may be related to the greater gross N transformation, Gly turnover rate and the increased expression of an amino acid transporter gene BcLHT1. Intact Gly contributed at most 6% to Gly-derived N at 24 h after tracer additions, which accounting for about 1.24% of the total N uptake in organic soil. Our study suggested that Gly-N and other organic source N might serve as a more important compensatory N source for plants in organic farming.  相似文献   

14.
Abstract. A number of organic farms in Flanders were sampled to investigate the general phosphorus (P) status and degree of P saturation (Psat) of the soils. Where possible, the soil P status was compared to that in conventional agriculture and related to farm characteristics: agricultural land use, soil texture, fertilization intensity and time since conversion. Generally, the P status of the organic farms was high, and similar to that of conventional farms in Flanders, which is due to the restricted time since conversion to organic farming on most farms. The average soil Psat was slightly lower (37%) than the average value for East Flanders (39%) taken over the soil profile to 90 cm. However, a large proportion of the field areas on organic farms still had a Psat greater than 30% (critical Psat value), which may be an indication that P saturation will continue to be a problem for these farms.  相似文献   

15.
A field experiment was conducted for 5 years (2004–2005 to 2009–2010) covering 10 crop seasons [five wet (WS; Kharif) and five dry (DS; Rabi)] at the Directorate of Rice Research farm, Hyderabad, India, to compare the influence of organic and conventional farming systems on productivity of fine grain rice varieties, cumulative partial nutrient balance, and soil health/quality in terms of nutrient availability, physical and biological properties, and sustainability index. Two main plot treatments were with and without plant protection measures, and four subplot treatments were (1) control (CON), (2) inorganic fertilizers (CF), (3) organics (OF), and (4) inorganics + organics (integrated nutrient management, INM). During wet season, grain yields with CF and INM were near stable (5.0 to 5.5 t ha?1) and superior to organics by 15–20% during the first 2 years, which improved with OF (4.8 to 5.4 t ha?1) in the later years to comparable levels with CF and INM. However, during DS, CF and INM were superior to OF for 4 consecutive years and OF recorded yields on par with CF and INM in the fifth year. The partial nutrient balance over 10 crop seasons for N and P was positive and greater with OF and INM over CF and for K it was positive with OF alone and negative with CF and INM. There were increases in SOC and available N, P, and K by 50–58%, 3–10%, 10–30%, and 8–25% respectively, with OF, over CF at the end of 5 years. The sustainability index (SI) of the soil system was maximum with organics (1.63) and CF recorded 1.33, which was just above the minimum sustainability index of 1.30 after 5 years. Thus, organic farming needs more than 2 years to stabilize rice productivity and bring about perceptible improvement in soil quality and sustainability in irrigated rice.  相似文献   

16.
The aim of this study was to evaluate the interaction between yield levels of nonleguminous crops and soil organic matter (SOM) under the specific conditions of organic and conventional farming, respectively, and to identify implications for SOM management in arable farming considering the farming system (organic vs. conventional). For that purpose, correlations between yield levels of nonlegume crops and actual SOM level (Corg, Nt, Chwe, Nhwe) as well as SOM‐level development were examined including primary data from selected treatments of seven long‐term field experiments in Germany and Switzerland. Yield levels of nonlegume crops were positively correlated with SOM levels, but the correlation was significant only under conditions of organic farming, and not with conventional farming treatments. While absolute SOM levels had a positive impact on yield levels of nonlegumes, the yield levels of nonlegumes and SOM‐level development over time correlated negatively. Due to an increased demand of N from SOM mineralization, higher yield levels of nonlegumes obviously indicate an increased demand for OM supply to maintain SOM levels. Since this observation is highly significant for farming without mineral‐N fertilization but not for farming with such fertilization, we conclude that the demand of SOM‐level maintenance or enhancement and thus adequate SOM management is highly relevant for crop production in organic farming both from an agronomical and ecological point of view. Under conventional management, the agronomic relevance of SOM with regard to nutrient supply is much lower than under organic management. However, it has to be considered that we excluded other possible benefits of SOM in our survey that may be highly relevant for conventional farming as well.  相似文献   

17.
《Applied soil ecology》2002,19(2):147-160
Field experiments were conducted to examine the effects of organic and synthetic soil fertility amendments on soil microbial communities and soil physical and chemical properties at three organic and three conventional vegetable farms in Virginia and Maryland in 1996 and 1997. Two treatments, including either an alternative organic soil amendment (composted cotton-gin trash, composted yard waste, or cattle manure) or synthetic soil amendment (fertilizer) were applied to three replicated plots at each grower field location. Production history and time affected propagule densities of Trichoderma species which remained higher in soils from organic farms. Propagule densities of Trichoderma species, thermophilic microorganisms, and enteric bacteria were also detected in greater numbers in soils amended with alternative than synthetic amendments, whereas propagule densities of Phytophthora and Pythium species were lower in soils amended with alternative than synthetic fertility amendments. Concentrations of Ca, K, Mg, and Mn were higher in soils amended with alternative than synthetic fertility amendments. Canonical correlations and principle component analyses indicated significant correlation between these soil chemical factors and the biological communities. First-order canonical correlations were more negative in fields with a conventional history, and use of synthetic fertilizers, whereas canonical correlations were more positive in fields with a history of organic production and alternative soil amendments. In the first year, yields of corn or melon were not different in soil amended with either synthetic or organic amendments at four of six farms. In the second year, when all growers planted tomatoes, yields were higher on farms with a history of organic production, regardless of soil amendment type. Alternative fertility amendments, enhanced beneficial soil microorganisms reduced pathogen populations, increased soil organic matter, total carbon, and cation exchange capacity (CEC), and lowered bulk density thus improving soil quality.  相似文献   

18.
The aim of this work was to investigate the response of soil microbial biomass and activity to practices in organic and conventional farming systems. The study was carried out at the Irrigation District of Piauí, Brazil. Five different plots planted with “acerola” orchard (Malpighia glaba) and established at the following management were evaluated: (1) under 12 months of soil conventional management (CNV); (2) under six months of soil organic management (ORG6); (3) under 12 months of soil organic management (ORG12); (4) under 18 months of soil organic management (ORG18); and (5) under 24 months of soil organic management (ORG24). Soil microbial biomass C (Cmic), basal respiration, organic carbon (Corg), Cmic-to-Corg ratio and metabolic quotient (qCO2) were evaluated in soil samples collected at 0–10 cm depth. The highest Corg and Cmic levels occurred in organic system plots ORG18 and ORG24 compared to the conventional system. Soil respiration and Cmic-to-Corg ratio were significantly enhanced by the organic system plots. The qCO2 was greater in conventional than in organic system. These results indicate that the organic practices rapidly improved soil microbial characteristics and slowly increase soil organic C.  相似文献   

19.
[目的] 研究优化施肥对黄土高原地区新增耕地土壤质量和作物产量的影响,为新增耕地土壤建立合理的优化施肥处理和区域新造土地的健康可持续发展提供理论依据。[方法] 通过盆栽种植试验,评估有机肥处理（OF）、有机肥配施化肥处理（NP）、常规施肥处理（CF）对新增耕地土壤团聚体数量、结构稳定性、有机质含量和玉米产量的改良效应。[结果] CF处理下新整治耕地土壤有机质含量最低为7.08 g/kg,土壤水稳性大团聚含量低,结构稳定性差。与CF处理相比,优化施肥方式下的OF和NP处理显著提高了新增耕地土壤有机质含量和玉米产量（p<0.05）,>0.25 mm粒级大团聚体含量和团聚体稳定性显著提升,其中OF处理对新整治耕地土壤团聚体数量和稳定性的改善效果最佳。在0—10 cm土层,OF和NP处理下土壤有机质含量分别为12.67,11.79 g/kg,比CF处理分别提高了46.2%和36.1%。OF处理下水稳性团聚体MWD,GMD,R0.25值分别比CF处理高了62.5%,21.4%和148.3%,分形维数比CF处理降低了1.7%;NP处理下水稳性团聚体MWD,GMD,R0.25值分别比CF处理高了18.8%,3.6%和40.9%,分形维数比CF处理降低了0.4%。在10—20 cm土层,OF和NP处理下土壤有机质含量、团聚体数量和结构稳定性也得到一定的提升。土壤有机质含量与团聚体平均重量直径（MWD）、几何平均直径（GMD）呈显著正相关关系（p<0.001）。[结论] 优化施肥是有利于提升新整治耕地土壤结构稳定性、保肥特性和土地生产力的有效措施。  相似文献   

20.
ABSTRACT

This study aimed at understanding whether and how long-term organic rice farming affects soil carbon (C) and nitrogen (N) stocks and their mineralization potentials in submerged rice paddies in Tochigi, Japan. An incubation experiment was carried out to assess the impacts of internal nutrient cycling after organic farming (OF) for 4–5 years (4OF), 8–9 years (8OF), and 12 years (12OF), compared with a conventional rice field (CF). Soil samples were collected at 0–15 cm and 15–20 cm in flooded rice fields after harvest in October 2013. pH and bulk density at 0–15 cm were significantly lower in 12OF fields than in CF fields (by 0.22 unit pH and 17.5%, respectively). Compared with CF, 12OF fields showed significant differences in soil organic carbon (SOC) and total nitrogen (TN), but 4OF and 8OF fields did not. In 8OF fields, the C decomposition (Co) and N mineralization (No) potentials were significantly higher (by 34.0% and 35.6%, respectively, at 0–15 cm, and by 67.1% and 24.5% at 15–20 cm) than in CF fields. Similarly, in 8OF fields at 0–15 cm, the Co:SOC and No:TN ratios were 19.8% and 23.2% higher, respectively, than in CF fields. Co, No, Co:SOC, and No:TN in 12OF fields were higher than those in CF fields, demonstrating the effects of prolonged organic rice farming. Additionally, in 12OF fields, C and N stocks were significantly higher (by 15.5% and 17.2%, respectively, at 0–15 cm, and by 4.8% and 12.1% at 15–20 cm) than in CF fields. Our findings suggest that long-term organic rice farming increases soil C and N stocks as well as C and N mineralization in Japanese Andosols.  相似文献   

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