首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 93 毫秒
1.
Increasing recognition of S deficiency in soils has raised the need for understanding processes governing S cycling and availability in soils. However, the quantification of the two main processes of S cycling, i.e. mineralization and immobilization, remains difficult as these processes occur simultaneously. A modified isotope 35SO4 dilution technique was developed and used to measure the effect of sulphate (SO4) fertilization on S mineralization and immobilization in planted (pot experiment with ryegrass (Lolium multiflorum L.)) and unplanted soils (incubation). The immobilization and mineralization of S was calculated from the dynamics of stable and labelled S in soil KH2PO4 extracts containing an anion exchange membrane that concentrates SO4 and mainly excludes other S species. The mathematical analysis of the isotope dilution data differs from methods proposed earlier. The radiolabile S in unplanted soil (E value) and in ryegrass (L value) were used as a measure of total available S in soils. Sulphate immobilization rate significantly declined during incubation. Sulphate application reduced gross mineralization but surprisingly reduced SO4 immobilization. The E value significantly increased during the incubation in all soils as a result of gross mineralization, e.g. from 3.8 mg S kg−1 at day 0 to 11.5 mg S kg−1 at day 43 in the sandy soil with no sulphate addition. A full recovery in the E value of S added in (+S) treatments was achieved. Similarly, radiolabile S in the above-ground ryegrass biomass (L value) increased with S addition, with a full recovery of added S. The E and L values nearly fit a 1:1 line suggesting identical S dynamics in a planted and unplanted soil. The method proposed has operational advantages compared to methods used earlier.  相似文献   

2.
 An open incubation technique was used to measure S mineralization in a range of upland soils of north China. Six mineralization patterns were examined, and a soil S-exhaustion experiment with ryegrass (Lolium multiflorum L.) was conducted to investigate the availability of various organic S pools to plants. For all of the 12 soils tested, the release of S as SO4 2– was curvilinear with time, and during a 28-week incubation at 30  °C the amount of S mineralized ranged from 14.0 mg S kg–1 soil to 37.4 mg S kg–1 soil. A first-order model and Gompertz model appeared to best describe S mineralization. Examination of the soils after incubation revealed the bulk of the mineralized S was mainly derived from the C-bonded S pool, while the majority of mineralized S under soil S exhaustion by ryegrass was derived from the HI-reducible S pool. Received: 9 July 1998  相似文献   

3.
Abstract

This study was undertaken to assess the mineralization of sulfur (S) in laboratory conditions of three rice soils (Joydebpur, Faridpur, and Thakurgaon), receiving the following treatments: 1) control, 2) rice straw (Oryza sativa L.), and 3) pea vine (Pisum sativum L.). The organic residue (25 mg g‐1) was added and mixed with soil and glass beads (1:1, soil to bead ratio) and placed into a Pyrex leaching tube. The soils were flooded and incubated at 35°C, after which they were leached with deionized water at 1, 2,4, 8, and 12 weeks for analysis of SO4 and other chemical properties in the leachates. Potentially mineralizable S (So) and C (Co) pools and first‐order rate constants (Ks for S and Kc for C) in soils amended with rice straw and pea vine under flooded conditions were estimated using an exponential equation. The So and Ks varied considerably among the soils and types of added organic residues, and their values in rice straw and pea vine ranged from 8.70 to 29.55 and 0.124 to 0.732 mg S kg‐1 wk‐1, respectively. Except for the Thakurgaon soil, the So and Ks values in Joydebpur and Faridpur soils were higher in the unamended treatments. Higher So values in the unamended soils were probably due to less microbial activity to mineralize organic S from organic residues. The results indicate that the amount of SO4 in flooded soils amended with organic residues are dependent on soil type, nature of organic residues, and time of incubation. The Co and Kc values under flooded incubation were higher in residue amended soils than in unamended soils. Pea vine treated soils had higher Co and Kc values than the soils treated with rice straw.  相似文献   

4.
Net mineralization of sulfur and nitrogen was studied in three Canadian Prairie soils using two commonly used incubation methods. In the open system technique, where the soils were leached periodically II.3–11.8 μ g SO2?4 -S g?1 soil was mineralized in 17 weeks. Little mineralization or a net immobilization of sulfur (from 1.4 to 1.3 μ g SO2?4-S g?1 soil) was observed in a closed system where the soils were left undisturbed throughout incubation. Changes in the specific activity of 35S-labelled soil solution sulfate during the closed incubation indicated that mineralization-immobilization processes were occurring simultaneously resulting in minimal net changes in CaCl2-extractable SO2?4 concentrations. The amounts of mineralized nitrogen (32.6–57.8 μg N g?1 soil) were found to be independent of the incubation method employed.  相似文献   

5.
The mineralization of sulfur (S) was investigated in a Vertisol and an Inceptisol amended with organic manures, green manures, and crop residues. Field‐moist soils amended with 10 g kg—1 of organic materials were mixed with glass beads, placed in pyrex leaching tubes, leached with 0.01 M CaCl2 to remove the mineral S and incubated at 30 °C. The leachates were collected every fortnight for 16 weeks and analyzed for SO4‐S. The amount of S mineralized in control and in manure‐amended soils was highest in the first week and decreased steadily thereafter. The total S mineralized in amended soils varied considerably depending on the type of organic materials incorporated and soil used. The cumulative amounts of S mineralized in amended soils ranged from 6.98 mg S (kg soil)—1 in Inceptisol amended with wheat straw to 34.38 mg S (kg soil)—1 in Vertisol amended with farmyard manure (FYM). Expressed as a percentage of the S added to soils, the S mineralized was higher in FYM treated soils (63.5 to 67.3 %) as compared to poultry manure amended soils (60.5 to 62.3 %). Similarly the percentage of S mineralization from subabul (Leucaena leucocephala) loppings was higher (53.6 to 55.5 %) than that from gliricidia (Gliricidia sepium) loppings (50.3 to 51.1 %). Regression analysis clearly indicated the dependence of S mineralization on the C : S ratio of the organic materials added to soil. The addition of organic amendments resulted in net immobilization of S when the C : S ratio was above 290:1 in Vertisol and 349:1 in Inceptisol. The mineralizable S pool (So) and first‐order rate constant (k) varied considerably among the different types of organic materials added and soil. The So values of FYM treated soils were higher than in subabul, gliricidia, and poultry manure treated soils.  相似文献   

6.
The effects of 15N-labelled urea, (NH4)2SO4 and KNO3 on immobilization, mineralization, nitrification and ammonium fixation were examined under aerobic conditions in an acid tropical soil (pH 4.0) and in a neutral temperate soil (pH 6.8). Urea, (NH4)2SO4 and KNO3 slightly increased net mineralization of soil organic nitrogen in both soils. There was also an apparent Added Nitrogen Interaction (ANI) i.e. added labelled NH4-N stood proxy for unlabelled NH4-N that would otherwise have been immobilized. So far as immobilization and nitrification were concerned, urea and (NH4)2SO4 behaved very similarly in each soil. Immobilization of NO3-N was negligible in both soils. Some of the added labelled NH4-N was rapidly fixed, more by the temperate soil than by the tropical soil. This labelled fixed NH4-N decreased during incubation, in contrast to labelled organic N, which did not decline.  相似文献   

7.
Abstract

This study was undertaken to assess the mineralization of nitrogen (N) in rice soils amended with organic residues under flooded condition. A lab incubation study with a 3x3 factorial design (two replications) was conducted with three rice soils (Joydebpur, Faridpur, and Thakurgaon) receiving the following treatments: 1) control, 2) rice straw (Oryza sativa L.), or 3) pea vine (Pisum sativum L.). The organic residue (25 mg straw g‐1 soil) was mixed with soil and glass beads (1:1, soil to beads ratio), and transferred into a Pyrex leaching tube, flooded and then incubated at 35°C for up to 12 weeks. The soils in the leaching tubes were leached (while maintaining flooded condition) at 1,2,4, 8, and 12 weeks with deionized water for determination of NH4‐N, NO3‐N, pH, and Eh. Nitrogen mineralization in soils amended with rice straw was somewhat different than that of soils treated with pea vine. Soil treated with rice straw had a higher N mineralization rate than soils treated with pea vine, which was due to a lower carbon (C):N ratio for rice straw. The potentially mineralizable N pool (No) in soils amended with rice straw and pea vine under flooded conditions, estimated using a 1st order exponential equation, were 7 to 15 times, and 3 to 9 times greater for rice straw No values and pea vine, respectively, than the control. The KN values for unamended soils ranged from 0.35 to 0.52 mg N kg‐1 wk‐1 and rice straw and pea vine treated soils were from 0.75 to 1.22 and 0.46 to 0.58 mgN kg‐1 wk‐1. The lower No and KN values in pea vine treatments suggested there was greater immobilization of N than in rice straw treatments.  相似文献   

8.
Soil was amended with 14C-labelled unripe straw only (C:N ratio ca. 20), with 14C-labelled unripe straw plus unlabelled ripe straw (C:N ratio ca. 100) or with 14C-labelled unripe straw plus glucose. Half the samples with 14C-labelled straw and half the samples with 14C-labelled plus unlabelled straw were cropped with rape plants. A decreased rate of mineralization of the 14C-labelled straw was found in the planted soil compared with the unplanted soil. The reduction was most profound in the soil amended with both labelled and unlabelled straw, indicating that at least part of the reduction was due to competition between plants and microorganisms for mineral N. No other explanations for the decrease in mineralization in the presence of plants were found. The soil amended with glucose which simulated the effect of root exudates showed an increased rate of mineralization. Therefore, the reduction in the presence of plants was probably not due to microbial use of the rhizodeposition in favour of the labelled straw. Only a minor part of the reduction was apparently due to uptake of labelled C by the plant, as only small amounts were found in the roots and shoots at harvest. The difference in 14C mineralization between treatments was not reflected in the number of bacteria in the soil at harvest. The number of bacteria, which was determined by plate counts and direct microscopy, was the same in all the soils, rhizosphere soils as well as bulk soils.  相似文献   

9.
The substitution of the widely practiced crop‐residue burning by residue incorporation in the subtropical zone requires a better understanding of factors determining nutrient mineralization. We examined the effect of three temperature (15°C, 30°C, and 45°C) and two moisture regimes (60% and 90% water‐filled pore space (WFPS)) on the mineralization‐immobilization of N, P, and S from groundnut (Arachis hypogae) and rapeseed (Brassica napus) residues (4 t ha–1) in two soils with contrasting P fertility. Crop‐residue mineralization was differentially affected by incubation temperature, soil aeration status, and residue quality. Only the application of groundnut residues (low C : nutrient ratios) resulted in a positive net N and P mineralization within 30 days of incubation, while net N and P immobilization was observed with rapeseed residues. Highest N and P mineralization and lowest N and P immobilization occurred at 45°C under nearly saturated soil conditions. Especially net P mineralization was significantly higher in nearly saturated than in aerobic soils. In contrast, S mineralization was more from rapeseed than from groundnut residues and higher in aerobic than in nearly saturated soil. The initial soil P content influenced the mineralization of N and P, which was significantly higher in the soil with a high initial P fertility (18 mg P (kg soil)–1) than in the soil with low P status (8 mg P (kg soil)–1). Residue‐S mineralization was not affected by soil P fertility. The findings suggest that climatic conditions (temperature and rainfall‐induced changes in soil aeration status) and residue quality determine N‐ and S‐mineralization rates, while the initial soil P content affects the mineralization of added residue N and P. While the application of high‐quality groundnut residues is likely to improve the N supply to a subsequent summer crop (high temperature) under aerobic and the P supply under anaerobic soil condition, low‐quality residues (rapeseed) may show short‐term benefits only for the S nutrition of a following crop grown in aerobic soil.  相似文献   

10.
We examined the effects of salicylate, glutamate and glucose on sulphur (S) immobilization and re‐mineralization in three calcareous soils: from arable, fallow and forest managements. Each of the three substrates, at a single rate of carbon (1000 mg C kg−1 soil) was added to the three soils and then incubated with NaSO4 plus Na2SO4 for 1, 2, 6 or 12 weeks prior to analysis. The extraction of the immobilized S was performed with either hot water (HW‐S) or 3 m hydrochloric acid (HCl‐S). Except for the forest soil, the average amounts of immobilized S increased in the order control < salicylate < glutamate < glucose. Across all soils, substrate addition significantly decreased the average value of HCl‐S expressed as a percentage of immobilized S compared with that of the control. The decreases in HCl‐S (58 − 100%) were substrate‐ and time‐independent, suggesting a heterogeneous action of HCl. In contrast, except for the forest soil, we found substantial declines in the average percentage values of HW‐S (21 − 75% of the immobilized S) in the order control > salicylate > glutamate = glucose, suggesting that the hot‐water action was substrate dependent. In addition, the proportion of HW‐S decreased with increasing incubation time, indicating that the youngest immobilized S was the most labile. Thus, hot water extracted more homogeneous S compounds than HCl. Sulphur immobilization induced by glutamate and glucose produced more recalcitrant S products (small quantities of 35S re‐mineralization) than that induced by salicylate. Glutamate tended to generate more recalcitrant S compounds than glucose. Hot‐water extractable S was a valuable and rapid indicator of readily labile organic S. Consequent microbial S immobilization resulting from glucose or glutamate addition was followed by a small rate of re‐mineralization of immobilized S.  相似文献   

11.
Abstract

Laboratory incubation and greenhouse experiments were conducted with two soils having contrasting physico‐chemical characteristics to evaluate nitrogen (N) mineralization, immobilization in soil microbial biomass, and accumulation in Japanese mint (Mentha arvensis L.) using labeled (15NH4)2SO4, applied at 0, 50, and 100 mg#lbkg‐1 soil. Rate of mineralization in soils varied from 0.08 to 2.21 μg#lbg‐1#lbday‐1. Fertilizer application increased the mineralization of native soil N. About 22 to 60% of the applied 15N was recovered in the soil microbial biomass during the growth period of mint (January‐June). Relative contribution of fertilizer 15N towards total N uptake by mint at maturity was 42–54% in soil I and 35 to 55% in soil II. Contribution of soil N towards total N accumulation increased with the doses of 15N application.  相似文献   

12.
Through their effects on microbial metabolism, temperature and moisture affect the rate of decomposition of soil organic matter. Plant roots play an important role in SOM mineralization and nutrient cycling. There are reports that rhizosphere soil exhibits higher sensitivity to temperature than root-free soil, and this can have implications for how soil CO2 efflux may be affected in a warmer world. We tested the effects of 1-week incubation under different combinations of temperature (5, 15, 30 °C) and moisture (15, 50, 100% WHC) on the respiration rate of soil planted with Scots pine and of unplanted soil. Soil respiration in both soils was the highest at moderate moisture (p < 0.0001) and, increased with temperature (p < 0.0001). There was also marginally significant effect of soil kind on respiration rate (p < 0.055), but the significant interaction of temperature effect with soil kind effect, indicated, that soil respiration of planted soil was higher than unplanted soil only at 5 °C (p < 0.05). The soil kind effect was compared also as Q10 coefficients for respiration rate, showing the relative change in microbial activity with increased temperature. However, there was no difference in the thermal sensitivity of soil respiration between planted and unplanted soils (p = 0.99), irrespective of the level of soil moisture. These findings were similar to the latest studies and confirmed, that in various models, being useful tools in studying of soil carbon cycling, there is no need to distinguish between planted and unplanted soil as different soil carbon pools.  相似文献   

13.
A laboratory incubation experiment was conducted to study the effect of indigenous inorganic N on the immobilization of applied N and on the occurrence of an added N interaction (ANI). Samples of six Mollisols from Illinois were incubated with 15N-labelled (NH4)2SO4 (100 or 200 mg N kg-1 soil), with or without the use of 0.01 M CaCl2 to extract inorganic N (mainly NO inf3 sup- ) before incubation. From 6 to 49% of the N applied was immobilized, higher percentages being obtained with unextracted soils than with the extracted soils and with the higher rate of N addition. Net mineralization of native N occurred in both the unextracted and extracted soils, but was more extensive in the unextracted soil and increased with the addition of N. The increases were accompanied by a positive ANI, which usually exceeded the amount of applied N immobilized and increased with the rate of addition. The ANI values observed with extracted soils were attributed to increased mineralization of native organic N.  相似文献   

14.
Predicting nitrogen (N) and sulfur (S) mineralization of crop residues from the preceding crop might be a useful tool for forecasting soil N and S availability. Two soils from eastern North Dakota and three crop residues – corn, spring wheat, and soybean were used in an 8-week incubation study to estimate N and S mineralization from crop residues. The cumulative N and S mineralized were fit to a first-order kinetic model. Cumulative N mineralized ranged between 0.34 and 2.15 mg kg?1 and 0.45 to 3.41 mg kg?1 for the Glyndon and Fargo soils, respectively. Un-amended soils showed higher N mineralization than residue treated soils. For S, the highest mineralization occurred in un-amended Glyndon soil and in spring wheat-amended Fargo soil. This study indicates that crop residue additions can have a negative impact on plant available nutrients due to immobilization of N and S during the time when crops need the nutrients most.  相似文献   

15.
Solar vegetable greenhouse soils show low soil organic carbon content and thus also low rates of soil respiration. Processing vegetable residues to biochar and mixing biochar with maize straw might improve soil respiration and increase soil organic carbon stocks, while preventing the spread of soil-borne diseases carried by vegetable residues. In an incubation experiment, we tested how additions of maize straw (S) and biochar (B) added in varying ratios (100S, 75S25B, 50S50B, 25S75B, 100B and 0S0B (control)) affect soil respiration and fraction of added C remaining in soil. Daily CO2 emissions were measured over 60 days incubation, the natural abundance of 13C in soil and in the added biochar and maize straw were analysed. Our result shows that (a) soil CO2 emissions were significantly increased compared to soil without the straw additions, while addition of biochar only decreased soil respiration; (b) cumulative CO2 emissions decreased with increasing ratio of added biochar to maize straw; (c) the abundance of soil 13C was significant positively correlated with cumulative CO2 emissions, and thus with the ratio of straw addition. Our results indicate that incorporation of maize straw in greenhouse soils is a meaningful measure to increase soil respiration and to facilitate greenhouse atmosphere CO2 limitation while producing vegetables. On the other hand, additions of biochar from vegetable residues will increase soil organic carbon concentration. Therefore, the simultaneous application of maize straw and biochar obtained from vegetable residues is an effective option to maintain essential soil functions for vegetable production in sunken solar greenhouses.  相似文献   

16.
Nitrogen mineralization and immobilization were investigated in two soils incubated with ammonium sulphate or pig slurry over a range of temperatures and moisture contents. A reduction in the mineralization of soil organic N was observed in soils incubated with 100 μg NH4+-Ng?1 soil as ammonium sulphate at 30°C but not at lower temperatures. Addition of 100 μg NH4+-N g?1 soil as pig slurry resulted in a period of nett immobilization lasting up to 30 days at 5°C. Although the length of the immobilization phase was shorter at higher temperatures the total N immobilized was similar. The subsequent rate of mineralization in slurry-treated soils was not significantly greater (P = 0.05) than in untreated soils. There was no evidence of any subsequent increased mineralization arising from the immobilized N or slurry organic N for up to 175 days. The rate of immobilization was found to increase with increasing moisture content, though the period of nett immobilization was shorter, so that the amount of N immobilized was similar over a range of moisture contents from 10 to 40%. Approximately 40% of the NH4+-N in the slurry was immobilized under the incubation conditions used.  相似文献   

17.
Organic N solubilized by NH3(aq) was extracted from 15N-labelled or unlabelled soil, concentrated and added to non-extracted soil, which was incubated under aerobic conditions at 27±1°C. Gross N mineralization, gross N immobilization, and nitrification in soils with or without addition of unlabelled soluble organic N were estimated by models based on the dilution of the NH 4 + or NO inf3 sup- pools, which were labelled with 15N at the beginning of incubation. Mineralization of labelled organic N was measured by the appearance of label in the mineral N pool. Although gross N mineralization and gross N immobilization were increased in two soils between day 0 and day 7 following addition of unlabelled organic N solubilized by NH3(aq), there was no increase in net N mineralization. Solubilization of 15N-labelled organic N increased and the 15N enrichment of the soluble organic N decereased as the concentration of NH3(aq) added increased. A constant proportion of approximately one-quarter of the labelled organic N added at different rates to non-extracted soil was recovered in the mineral N pool after an incubation period of 14 days, and the availability ratios calculated from net N mineralization data were 1.1:1 and 2.1:1 for 111 and 186 mg added organic-N kg-1 soil, respectively, indicating that the mineralization of organic N was increased by solubilization.  相似文献   

18.
This investigation examines the effect of manipulating soil microbial community composition and species richness on the development of soil structure over a seven month period in planted (with or without mycorrhizal fungi) and in unplanted macrocosms. The dilution method effectively resulted in soil communities with consistently contrasting levels of species (TRF) richness. In particular, the 10?6 dilution of field soil resulted in less rich communities in bare unplanted soil than did the 10?1 soil dilution. However, this was not the case in planted soils where root activity was a powerful influence on species richness. After seven months, principal components analysis (PCA) separated bacterial community composition primarily on planting regime; planted mycorrhizal, planted non-mycorrhizal and bare soil treatments all contained different bacterial community compositions. A consistent finding in planted and unplanted soils was that aggregate stability was positively correlated with small pore sizes. Mycorrhizal colonisation decreased plant biomass and also resulted in reduced soil bacterial species richness, lower percentage organic matter and smaller pore sizes relative to planted but non-mycorrhizal soils. However, soil aggregate stability and water repellency were increased in these (mycorrhizal) soils probably due to AMF hyphal activities including enmeshment and/or glomalin production. In contrast, bacterial TRF richness was positively correlated with aggregate stability in the bare and non-mycorrhizal planted soils. Soil organic carbon was an important factor in all treatments, but in the bare soil where there was no additional input of labile C from roots, the percentage C could be directly related to fungal TRF richness. The less species rich bare soil contained more organic C than the more species rich bare soil. This suggests a degree of redundancy with regard to mineralisation of organic matter when additional, more utilisable C sources are unavailable. Understanding the effects of microbial diversity on functional parameters is important for advancing sustainable soil management techniques, but it is clear that soil is a dynamic ecosystem.  相似文献   

19.
Symbiotically-fixed and soil-derived nitrogen have been measured in pot experiments for Medicago littoralis (medic), grown alone or with Lolium multiflorum (ryegrass) and for Pisum sativum (field pea). The four soils used contained organic matter labelled with 15N, and differed in their capacities to release available N. During a 4–12-week incubation each released inorganic N (NO?3) of approximately constant 15N atom% enrichment. In one soil, the mineralized N was supplemented by 15NO?3 of similar 15N atom% enrichment. Incubation of soils under intermittently moist and dry conditions increased N mineralization rates, but did not affect the 15N atom% enrichments of the released N.For all soils and treatments the amounts of soil-derived N taken up by plants equalled the amounts of available N in moist incubated, unplanted soils. The enrichment of ryegrass root N grown alone or with medic was slightly but consistently less than that of top N. Nitrogen of the legume nodules and pods (peas) was least enriched, followed by N of legume stems, leaves and roots; the 15N atom% enrichments of root N were 4–5 times those of nodule N.Peas generally outyielded and fixed more N than medic grown alone. Medic grown with ryegrass yielded least and fixed least N.For unamended soils, yields of legume dry matter and amounts of N fixed were greatest in Roseworthy or Avon sandy loam soils and least in Northfield clay loam. Addition of 15NO?3 to Avon soil decreased N fixed by peas and by medic grown alone or with ryegrass. For this soil, soil-derived N of plant tops exceeded fixed N of roots, even for unamended soil where fixation by legumes was relatively high. Thus, complete removal of plant tops would have produced a net loss of N from the soil, the net loss increasing with increasing amounts of 15NO?3 added.  相似文献   

20.
Abstract

The fate of nitrogen (N) derived from soil incorporating 15N-labeled apple (Malus domestica) leaves and wood from pruning (hereafter referred to as “pruning wood”) was studied in an 8-month pot experiment. The net mineralization of N was measured as 15N recovery in perennial ryegrass (Lolium perenne) that was allowed to grow in soils amended with residues < 2 mm in size (litter : soil ratio, w/w, 1:250 for leaves and 1:330 for wood). The immobilization of native soil N as a consequence of residue addition was measured by comparing the amount of total N taken up by ryegrass in residue-amended soil and in control soil. Net immobilization of soil N occurred during the first 2 months after litter addition and was especially high in the soil amended with leaf litter. During the period of soil N immobilization, the amount of soil microbial N was high in the soils treated with both types of residues, while that of mineral N was markedly reduced only in the leaf-litter-amended soil. Net N uptake from the control soil almost stopped after 3 months of plant growth, while ryegrass in the litter-amended soil continued to take up N, indicating a likely release of previously immobilized N. Net mineralization of the 15N from apple residues was slow during the first 2 months after their incorporation and then increased. In total, 6% (leaves) and 12% (wood) of the N added via residues underwent mineralization, while 67% (leaves) and 85% (wood) were found in the extractable soil N pool (humic and fulvic acids and non-humified fractions). The data indicated that, even if N was incorporated into the soil, apple leaves and pruning wood did not mineralize significant amounts of N in the short term. The evidence suggested that during the decomposition of both types of apple residues the N originally present was incorporated into the stable soil N pool.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号