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1.
The study was based on data from selected long-term field trials established at the Experimental Fields of the Institute of Field and Vegetable Crops, Novi Sad (Serbia). The effect of tillage systems on SOC concentration and SOC stock was most pronounced at 0–10 cm depth. In a 0–40 cm soil layer, in a 7-year period, no-till (NT) sequestrated 863 kg SOC ha?1 yr?1 more compared to moldboard plow tillage (PT), while the effects of disc tillage (DT) and chisel tillage (CT) were not significantly different. Unfertilized three-crop rotation (CSW) compared to two-crop rotation (CW) enhanced SOC storage in a 0–30 cm soil layer by 151 kg C ha?1 yr?1 in a 56-year period. Within fertilized treatments, SOC concentration was highest under continuous corn (CC). Mineral fertilization (F) non-significantly increased the SOC stock compared to no fertilization in corn monoculture in a 32-year period. The incorporation of mineral fertilizers and harvest residues (F + HR) and mineral fertilizers and farmyard manure (F + FYM) sequestered 195 and 435 kg C ha?1 yr?1 more than the unfertilized plot, respectively, in a 0–30 cm soil layer, in a 35-year period. Irrigation did not significantly affect SOC sequestration.  相似文献   

2.
Data from a 49-year-long organic–mineral fertilization field experiment with a potato–maize–maize–wheat–wheat crop rotation were used to analyse the impact of different fertilizer variations on yield ability, soil organic carbon content (SOC), N and C balances, as well as on some characteristic energy balance parameters. Among the treatments, the fertilization variant with 87 kg ha?1 year?1 N proved to be economically optimal (94% of the maximum). Approximately 40 years after initiation of the experiment, supposed steady-state SOC content has been reached, with a value of 0.81% in the upper soil layer of the unfertilized control plot. Farmyard manure (FYM) treatments resulted in 10% higher SOC content compared with equivalent NPK fertilizer doses. The best C balances were obtained with exclusive mineral fertilization variants (?3.8 and ?3.7 t ha?1 year?1, respectively). N uptake in the unfertilized control plot suggested an airborne N input of 48 kg ha?1 year?1. The optimum fertilizer variant (70 t ha?1 FYM-equivalent NPK) proved favourable with a view to energy. The energy gain by exclusive FYM treatments was lower than with sole NPK fertilization. Best energy intensity values were obtained with lower mineral fertilization and FYM variants. The order of energy conversion according to the different crops was maize, wheat and potato.  相似文献   

3.
A field experiment was conducted with the objectives to relate the changes in the physical properties, soil organic carbon (SOC), nutrient availability, and uptake and output input ratios for sustaining sugarcane ratoon growth and yield in an Udic ustochrept. Eight combinations of trash and farmyard manure (FYM) with and without Trichoderma viride and Gluconacetobacter diazotrophicus were applied in two sugarcane ratoon (first and second ratoon in succession) crops. Application of Trichoderma-enriched trash showed the lowest bulk density (1.36 Mg m?3) and the greatest infiltration rate (4.5 mm h?1). Greater rate of increase in SOC was observed under inoculation of Trichoderma with FYM compared to trash mulch. The output/input ratios were greater in plots having trash-based treatments compared to FYM and inorganic fertilizers. Bioagent-inoculated FYM produced greater mean sugar yield (8.89 t ha?1) compared to bioagent-inoculated trash (7.97 t ha?1).  相似文献   

4.
Biochar amendments offer promising potential to improve soil fertility, soil organic carbon (SOC) and crop yields; however, a limited research has explored these benefits of biochar in the arid and semi‐arid regions. This two‐year field study investigated the effects of Acacia tree biomass‐derived biochar, applied at 0 and 10 t ha?1 rates with farmyard manure (FYM) or poultry manure (PM) and mineral phosphorus (P) fertilizer combinations (100 kg P ha‐1), on maize (Zea mays L.) productivity, P use efficiency (PUE) and farm profitability. The application of biochar with organic–inorganic P fertilizers significantly increased soil P and SOC contents than the sole organic or inorganic P fertilizers. Addition of biochar and PM as 100% P source resulted in the highest soil P (104% increase over control) and SOC contents (203% higher than control). However, maize productivity and PUE were significantly higher under balanced P fertilizer (50% organic + 50% mineral fertilizer) with biochar and the increase was 110%, 94% and 170% than 100%‐FYM, 100%‐PM and 100% mineral fertilizer, respectively. Maize productivity and yield correlated significantly positively with soil P and SOC contents These positive effects were possibly due to the ability of biochar to improve soil properties, P availability from organic–inorganic fertilizers and SOC which resulted in higher PUE and maize productivity. Despite the significant positive relationship of PUE with net economic returns, biochar incorporation with PM and mineral fertilizer combination was economically profitable, whereas FYM along biochar was not profitable due to short duration of the field experiments.  相似文献   

5.
ABSTRACT

Soil organic carbon (SOC) is a key component for sustaining crop production. A field experiment was conducted during 2004–2018 to assess the changes in soil carbon fractions under different fertilization practices in grass-legumes mixture. The result indicates that application of farmyard manure (FYM) at 80 Mg ha–1 has increased SOC concentration leading to carbon sequestration rate of 4.2 Mg ha–1 year–1. Further, it has increased the proportion of labile carbon in the total SOC and have accumulated 126, 60, 83 and 95% higher very labile, labile, less labile and non-labile C stock than that of control plot, respectively, in top 30 cm soil layer. Inorganic fertilization and FYM 20 Mg ha–1 influenced SOC concentration, SOC stock and C sequestration rate similarly. The highest carbon management index (264) was found in the treatment receiving FYM 80 Mg ha–1 and it was positively correlated with SOC (r = 0.84**). The sensitivity index of the SOC varied from 26 to 152% and the differences were greatest in FYM treatments. The result indicates that grass-legumes mixture build-up the SOC in long term and the addition of FYM further increases it.  相似文献   

6.
A long‐term fertilization experiment with monoculture corn (Zea mays L.) was established in 1980 on a clay‐loam soil (Black Soil in Chinese Soil Classification and Typic Halpudoll in USDA Soil Taxonomy) at Gongzhuling, Jilin Province, China. The experiment aimed to study the sustainability of grain‐corn production on this soil type with eight different nitrogen (N)‐, phosphorus (P)‐, and potassium (K)–mineral fertilizer combinations and three levels (0, 30, and 60 Mg ha–1 y–1) of farmyard manure (FYM). On average, FYM additions produced higher grain yields (7.78 and 8.03 Mg ha–1) compared to the FYM0 (no farmyard application) treatments (5.67 Mg ha–1). The application of N fertilizer (solely or in various combinations with P and K) in the FYM0 treatment resulted in substantial grain‐yield increases compared to the FYM0 control treatment (3.56 Mg ha–1). However, the use of NP or NK did not yield in any significant additional effect on the corn yield compared to the use of N alone. The treatments involving P, K, and PK fertilizers resulted in an average 24% increase in yield over the FYM0 control. Over all FYM treatments, the effect of fertilization on corn yield was NPK > NP = NK = N > PK = P > K = control. Farmyard‐manure additions for 25 y increased soil organic‐matter (SOM) content by 3.8 g kg–1 (13.6%) in the FYM1 treatments and by 7.8 g kg–1 (27.8%) in the FYM2 treatments, compared to a 3.2 g kg–1 decrease (11.4%) in the FYM0 treatments. Overall, the results suggest that mineral fertilizers can maintain high yields, but a combination of mineral fertilizers plus farmyard manure are needed to enhance soil organic‐matter levels in this soil type.  相似文献   

7.
Soil organic carbon (SOC) sequestration in response to long-term fertilizer management practices under jute-rice-wheat agro-ecosystem in alluvial soils was studied using a modeling approach. Fertilizer management practices included nitrogen (N), phosphorus (P) and potassium (K) fertilization, manure application, and root-stubble retention of all three crops. Soil carbon (C) model RothC was used to simulate the critical C input rates needed to maintain initial soil C level in long timescale (44 years). SOC change was significantly influenced by the long-term fertilizer management practices and the edaphic variable of initial SOC content. The effects of fertilizer combination “100%NPK+FYM” on SOC changes were most significant over “100%NPK” fertilization. If the 100% NPK fertilizer along with manure applied with stubble and roots retention of all crops, alluvial soils of such agro-ecosystem would act as a net C sink, and the average SOC density kept increasing from 18.18 Mg ha?1 during 1972 to the current average of ～22 Mg ha?1 during 2065 s. On an average, the critical C input was estimated to be 5.30 Mg C ha?1 yr?1, depending on local soil and climatic conditions. The critical C input could be effectively estimated using a summary model driven by current SOC level, mean annual temperature, precipitation, and soil clay content. Such information will provide a baseline for assessing soil C dynamics under potential changes in fertilizer and crop residues management practices, and thus enable development of management strategies for effectively mitigating climate change through soil C sequestration.  相似文献   

8.
A long-term field experiment (1984–2011), was conducted on a Calcic Haploxeralf from semi-arid central Spain to evaluate the combined effect of three treatments: farmyard manure (FYM), straw and control without organic amendments (WOA) and five increasing rates of mineral N on: (1) some energetic parameters of crop production, and (2) the effect of the different treatments on soil organic carbon (SOC) and total N stocks. Crop rotation included spring barley, wheat and sorghum. The energy balance variables considered were net energy produced (energy output minus energy input), the energy output/input ratio and energy productivity (crop yield per unit energy input). Results showed small differences between treatments. Total energy inputs varied from 9.86 GJ ha?1 year?1 (WOA) to 11.14 GJ ha?1 year?1 in the FYM system. For the three crops, total energy inputs increased with increasing rates of mineral N. Energy output was slightly lower in the WOA (33.40 GJ ha?1 year?1) than in the two organic systems (37.34 and 34.96 GJ ha?1 year?1 for FYM and straw respectively). Net energy followed a similar trend. At the end of the 27-year period, the stocks of SOC and total N had increased noticeably in the soil profile (0–30 cm) as a result of application of the two organic amendments. Most important SOC changes occurred in the FYM plots, with mean increases in the 0–10 cm depth, amounting an average of 9.9 Mg C ha?1 (667 kg C ha?1 year?1). Increases in N stocks in the top layer were similar under FYM and straw and ranged from 0.94 to 1.55 Mg N ha?1. By contrast, simultaneous addition of increasing rates of mineral N showed no significant effect on SOC and total N storage.  相似文献   

9.
Abstract

The content of soil organic carbon (SOC) and total nitrogen (Ntot) was studied in a long-term field experiment with a three-field crop rotation (potato – spring wheat – spring barley) set up on arable sandy loam Stagnic Albeluvisol at Eerika, Tartu, Estonia. The studied factors were: (A) organic fertilizers with three treatments: (i) without organic fertilizer, (ii) farmyard manure (60 t ha?1) used in every third year, and (iii) different organic (alternative) fertilizers (beet leaves + straw; pure beet leaves; slurry + straw; cereal straw) and (B) mineral nitrogen fertilizer with the rates: N-0; N-40; N-80; N-120 and N-160 kg ha?1. The study years were 1993, 1996 and 1999. The average content of SOC (1.03%) was significantly influenced by the use of organic fertilizers. Only Ntot (mean value 0.110%) was influenced also by fertilization with mineral nitrogen. The C/N ratio (mean value 9.5) reflected changes in the content of SOC and Ntot  相似文献   

10.
A field experiment was conducted during 2008 and 2009 at the Council of Scientific and Industrial Research-Institute of Himalayan Bioresource Technology, Palampur, India, to study the effect of organic sources of nutrient on yield, nutrient uptake, fertility status of soil, and quality of stevia crop in the western Himalayan region. The experiment comprised eight different combinations of organic manure [farmyard manure (FYM), vermicompost (VC), and apple pomace manure (AP)]. Total leaf dry biomass increased by 149% over the control with application of VC 1.5 t ha?1 + AP 5 t ha?1. Application of organic manures enhanced organic carbon and available nutrient status of soil more than the control. Nitrogen (N) and phosphorus (P) content in stem were significantly affected by the application of organic manures over the control. Stevia plants supplied with FYM 10 t ha?1 + AP 2.5 t ha?1 recorded more total glycoside than other treatments. Stevioside yield (kg ha?1) was greater with application of FYM 10 t ha?1 + AP 2.5 t ha?1.  相似文献   

11.
In an ongoing field experiment, organic and conventional farming (control) were compared for onion bulb yield, biochemical quality, soil organic carbon (SOC), and microbial activity after the sixth cropping cycle. The treatments used for organic production were farmyard manure (FYM, 20,000 kg ha?1), poultry manure (PM, 10,000 kg ha?1), vermicompost (VC, 10,000 kg ha?1), neem cake (NC, 5000 kg ha?1), and a combination of FYM (5000 kg ha?1), PM (2500 kg ha?1), VC (2500 kg ha?1), and NC (1250 kg ha?1); all treatments were compared with the control. Organic treatments produced 24.6–43.6% lower yield consistently for 6 years than the control treatment. No significant difference was observed between PM, FYM, and VC treatments for the bulb yield. Bulb analysis during the sixth year indicated that plants that received FYM, PM, or VC had higher levels of total phenol, total flavonoid, ascorbic acid, and quercetin-3-glucoside than the control plants. All the five organically treated sets had significantly higher values of SOC, microbial population, fungal-to-bacterial ratio, and dehydrogenase activity than the control and the initial values in each treated set. The results indicate that FYM, PM, or VC application enhances biochemical quality and organic farming is more sustainable than conventional farming.  相似文献   

12.
A field experiment was conducted during the summer season of 2009 and 2010 at Vivekananda Parvatiya Krishi Anusandhan Sansthan, Hawalbagh, Almora, Uttarakhand, under the mid-hills of north-western Himalaya, to study the effect of farmyard manure and fertilizers on fruit yield, economics, energetics of pepper (Capsicum annuum L.) and on soil chemical properties. The highest level of farmyard manure (20 t ha?1) along with 125% of recommended NPK (125, 27.5, and 52.1 kg N, P and K ha?1) resulted in significantly higher fruit yield (33.9 t ha?1) over other combinations. Both farmyard manure and inorganic fertilizers significantly increased fruits/plant, average fruit weight, plant height, fruit length, and fruit diameter. The maximum net returns (4520 $ ha?1) was achieved at 20 t of FYM along with 125% of recommended NPK. Energy ratio of 1.29 and 1.13 was the highest under 20 t FYM ha?1 and 125% of recommended NPK, respectively. Available nutrients (N, P, and K) improved the status of the soil significantly due to 20 t ha?1 of FYM and 125% of recommended NPK over other treatments.  相似文献   

13.
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   

14.
Soil organic matter (SOM) contributes to the productivity and physical properties of soils. Although crop productivity is sustained mainly through the application of organic manure in the Indian Himalayas, no information is available on the effects of long-term manure addition along with mineral fertilizers on C sequestration and the contribution of total C input towards soil organic C (SOC) storage. We analyzed results of a long-term experiment, initiated in 1973 on a sandy loam soil under rainfed conditions to determine the influence of different combinations of NPK fertilizer and fertilizer + farmyard manure (FYM) at 10 Mg ha−1 on SOC content and its changes in the 0–45 cm soil depth. Concentration of SOC increased 40 and 70% in the NPK + FYM-treated plots as compared to NPK (43.1 Mg C ha−1) and unfertilized control plots (35.5 Mg C ha−1), respectively. Average annual contribution of C input from soybean (Glycine max (L.) Merr.) was 29% and that from wheat (Triticum aestivum L. Emend. Flori and Paol) was 24% of the harvestable above-ground biomass yield. Annual gross C input and annual rate of total SOC enrichment were 4852 and 900 kg C ha−1, respectively, for the plots under NPK + FYM. It was estimated that 19% of the gross C input contributed towards the increase in SOC content. C loss from native SOM during 30 years averaged 61 kg C ha−1 yr−1. The estimated quantity of biomass C required to maintain equilibrium SOM content was 321 kg ha−1 yr−1. The total annual C input by the soybean–wheat rotation in the plots under unfertilized control was 890 kg ha−1 yr−1. Thus, increase in SOC concentration under long-term (30 years) rainfed soybean–wheat cropping was due to the fact that annual C input by the system was higher than the required amount to maintaining equilibrium SOM content.  相似文献   

15.
The influence of differing soil management practices on changes seen in soil organic carbon (SOC) content of loamy Haplic Luvisol was evaluated. The field experiment included two types of soil tillage: 1. conventional tillage (CT) and 2. reduced tillage (RT) and two treatments of fertilization: 1. crop residues with nitrogen, phosphorus, and potassium (NPK) fertilizers (PR+NPK) and 2. NPK fertilizers (NPK). The results of SOC fluctuated from 9.8 to 14.5 g kg?1 and the tillage systems employed and fertilization status did not have a statistically significant influence on SOC. The SOC content was higher in RT (12.4 ± 0.86 g kg?1) than in CT (12.2 ± 0.90 g kg?1). On average, there was a smaller higher value of SOC in PR+NPK (12.4 ± 1.02 g kg?1) than in NPK (12.3 ± 0.88 g kg?1). During a period of 18 years, reduced tillage and application of NPK fertilizers together with crop residues build up a SOC at an average speed of 7 and 16 mg kg?1 year?1, respectively, however conventional tillage and NPK fertilizer applications caused a SOC decline at an average speed of 104 and 40 mg kg?1 year?1, respectively.  相似文献   

16.
The effects of integrated nitrogen management (INM) on saffron yield, corm production, nutrient concentration, crocin content, and soil health were studied in field experiments at the Dryland (Karewa) Agriculture Research Station, Budgam District of Kashmir Himalayas, India, during 2006–2010. The levels of fertilizers applied were 0, 45, and 90 kg ha?1 of nitrogen; 0, 30, and 60 t ha?1 of farm yard manure (FYM), and 0 and 5 kg ha ?1 of Azotobacter in solid form. The greatest yields of 3.64 and 3.51 kg ha?1 were observed when nitrogen was applied at 90 kg ha?1 and FYM was applied at 60 t ha?1. The increases over the controls (2.31 and 2.45 kg ha?1) were 57.57% and 43.26%, respectively. The maximum corm productions (10.26 and 13.10 t ha?1) were observed with the application of nitrogen at 90 kg ha?1 and FYM at 60 t ha?1 respectively, with the corresponding increases of 79.62% and 260.97% over their respective controls. Biofertilizer application in the form of viable strain of Azotobacter significantly increased the corm production only. The influence of INM on nutrient and crocin content of saffron and soil health was also found to be sustainable over nonapplication of organic and inorganic fertilizers.  相似文献   

17.
Management practices can have significant implications for both soil quality and carbon (C) sequestration potential in agricultural soils. Data from two long‐term trials (one at field scale and the other at lysimeter scale), underway in north‐eastern Italy, were used to evaluate the dynamics of soil organic carbon (SOC) and estimate the impact of recommended management practices (RMPs) on soil carbon sequestration. Potential SOC sequestration was calculated as the differences between the change in SOC of treatments differing only for the specified RMP for a period of at least 25 years. The trials compared the following situations: (a) improved crop rotations versus monoculture; (b) grass versus improved crop rotations; (c) residue incorporation versus residue removal; (d) high versus low rates of inorganic fertilizers; (e) integrated nutrient management/organic manures versus inorganic fertilizers. At the lysimeter scale, some of these treatments were evaluated in different soils. A general decrease in SOC (1.1 t C ha?1 year?1) was observed after the introduction of intensive soil tillage, evidencing both the worsening of soil quality and the contribution towards global CO2 emissions. Initial SOC content was maintained only in permanent grassland, complex rotations and/or with the use of large quantities of livestock manure. SOC sequestration reached a maximum rate of 0.4 t C ha?1 year?1 comparing permanent grassland with an improved crop rotation. Crop residue incorporation and rates of inorganic fertilizer had less effect on SOC sequestration (0.10 and 0.038 t C ha?1 year?1, respectively). The lysimeter experiment highlighted also the interaction between RMPs and soil type. Peaty soil tended to be a source of C independent of the amount and quality of C input, whereas a proper choice of tillage practices and organic manures enhanced SOC sequestration in a sandy soil. The most promising RMPs in the Veneto region are, therefore, conversion to grassland and use of organic manures. Although some of these RMPs are already supported by the Veneto Region Rural Development Plan, their more intensive and widespread implementation requires additional incentives to become economically feasible.  相似文献   

18.
ABSTRACT

The effects of long-term (1959–2005) liming in combination with cattle manure application on the chemical properties and aggregate stability of acid soil were investigated in the whole soil profile to a 100 cm depth. Investigations were performed in a long-term liming and fertilizing field trial at Vezaiciai Branch of Lithuanian Research Centre for Agriculture and Forestry situated in West Lithuania. The soil of the study site is Bathygleyic Distric Glossic Retisol (WRB 2014) with a texture of moraine loam. Acid soil had been periodically limed and manured at different intensity for 47 years. The experiment involved the following treatments: (1) unlimed and unfertilized (control); (2) unlimed and 60 t ha?1 manure; (3) limed and unfertilized; and (4) limed and 60 t ha?1 manure. During the 47-year period, liming was performed using pulverized limestone at a rate 1.0 (by hydrolytic soil acidity) every 7 years. During the whole study period, the soil received 38.7–36.5 t ha?1 CaCO3; 840 t ha?1 cattle manure, 2740 kg ha?1 mineral nitrogen; 3030 kg ha?1 phosphorus and 3810?kg?ha?1 potassium. The data showed that long-term (47 years) periodic liming of different intensities in combination with cattle manure application significantly changed the chemical properties of the whole soil profile. The soil acidification was neutralized in the topsoil and subsoil to the 60?cm depth when the soil had been systematically limed with 1.0 rate every 7 years in combination with 60?t?ha?1 manure application every 3–4 years. Periodic long-term liming in combination with manuring had a positive effect on the improvement of chemical properties of acid soil profile in the ElB1 and ElB2 horizons. The data of the soil structure in the topsoil and subsoil showed that such liming practice together with manuring had a positive effect on soil aggregate stability.  相似文献   

19.
In this study, 24 years (1990–2013) of data from a long-term experiment, in Stillwater, Oklahoma (OK), were used to determine the effect of beef manure on soil test phosphorus (STP), soil organic carbon (SOC), and winter wheat (Triticum aestivum L.) yield. Beef manure was applied every 4 years at a rate of 269 kg nitrogen (N) ha?1, while inorganic fertilizers were applied annually at 67 kg N ha?1, 14.6 kg phosphorus (P) ha?1, and 27.8 kg potassium (K) ha?1 for N, P, and K, respectively. Averaged across years, application of beef manure, and inorganic P maintained STP above 38 mg kg?1 of Mehlich-3 extractable P, a level that is far beyond crop requirements. A more rapid decline in SOC was observed in the check plot compared to the manure-treated plot. This study shows that the application of animal manure is a viable option to maintaining SOC levels, while also optimizing grain yield.  相似文献   

20.
Nitrate leaching, overall N balance, and organic‐C build‐up in a semi‐arid agro‐ecosystem in NW India was estimated from the results of a long‐term manurial trial with farmyard manure (FYM) and mineral‐N fertilizer in operation since 1967 at the Research Farm of CCS Haryana Agricultural University, Hisar, India. The model LEACHN was calibrated for the wheat‐growing period November 2000 to April 2001 and the leaching of nitrate during this period was predicted to 48 kg N ha–1 without mineral‐N fertilization and 59 kg N ha–1 with addition of 120 kg mineral‐N fertilizer, both with the addition of 15 t ha–1 FYM. The N balance for the simulation period showed that the 120 kg N ha–1–mineral N fertilization compared to zero mineral N, both plus FYM, resulted in only slightly higher crop uptake, leaching losses, and NH3 volatilization, and a negligible increase of N in organic matter. The largest amount remains as an additional build‐up of mineral N in the profile (84.3 kg N ha–1) which is prone to losses as ammonia or nitrate. The model was used to simulate organic‐C build‐up with FYM and a decrease of organic C without FYM for a period of 33 y (1967–2000). The simulated C build‐up to about 0.1 g kg–1 agreed very well with the measured values and showed that additional mineral‐N fertilization will not have any significant effect on organic‐C content. Simulations with the assumption of no FYM application showed a gradual decrease of organic C from its starting value of 0.046 g kg–1 in 1967 down to almost half of this. This agreed well with the observed organic‐C values of 0.028 g kg–1 as measured for unmanured plots.  相似文献   

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