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Widespread presence of plastic mulch has led to macroplastic (MaP) pollution. While this issue is widely explored in aquatic ecosystems, MaP pollution on land has been neglected. In 2019, we conducted a large-scale survey of MaPs in Northwest China in 0-30 cm soil with long-term mulching. Samples of MaP debris were collected from 67 sites across Gansu, east Qinghai, and north Shannxi Provinces. All visible MaP pieces for each site were separated and weighed. The mass of each MaP piece was calibrated by size measured in digital images. The MaP mass averaged 47.2 kg ha

Small farms are the mainstay of maize production in China. Its productivity is relatively low despite large farm inputs and the associated environmental footprints. Here, we studied public–private partnership (PPP) model for sustainable intensification of maize production to achieve co‐benefits of food security and environmental sustainability. The PPP model enabled the development of an effective partnership by bringing complementary skills, knowledge, proprietary products and technologies, and resources of public research community and private enterprises to create a new, operational maize farming system in China. We conducted on‐farm research with farmer participation in four major maize‐growing regions spanning temperate to sub‐tropical zones in China for 2 years. The PPP model achieved 78.7% of maize yield potential compared with 61.8% realized in smallholder farm (SHF) (11.0 Mg ha−1 vs. 8.6 Mg ha−1). Overall, environmental externalities of PPP were up to 32.7% lower than that of SHF, depending on the region studied. PPP significantly reduced reactive nitrogen losses by 31.3%–35.5% compared with SHF in both years. There was no significant difference between PPP and SHF for greenhouse gas emission in 2018, but it was significantly lower in PPP (19%) compared to SHF in 2019. Similarly, PPP significantly reduced soil acidification potential (by 10.1%–42.2%) and eutrophication of waterbodies (21.5%) in comparison to SHF. Overall, the net ecosystem economic budget increased 277 USD ha−1 with PPP. The PPP model provides new insights into improving food security and ecosystem and economic budget. As a logical progression to our research, future work should focus on (a) the reasons for the persistence of inter‐regional yield gap in PPP model and (b) to gain a better understanding of socioeconomic drivers critical for successful PPP in different maize‐growing regions.

Film fully-mulched ridge–furrow (FMRF) water harvesting, film mulched conventional flat planting with one-half (FMCF) and two-thirds (FTMCF) has been widely adopted in Northern China. However, it is unclear whether sustainability are. An 8-year corn yield in these three systems was investigated at Zhenyuan of East Gansu in 2008 to 2015, and a 4-year location study with FMRF and FMCF, three corn hybrids, and three densities was conducted at Pengyang of South Ningxia from 2012 to 2015. The results indicated that FMRF with rain-harvesting efficiency of 65.7%–82.7% makes rainwater infiltrate deep soil and soil moisture double increase in furrow root-zone. The 8-year average grain yield increased by 22.7% in FMRF and 14.5% in FTMCF compared with FMCF. In the 4-year field trail, rainfall and its seasonal distribution highly impacted grain yield and water-use efficiency (WUE), but order of importance for grain yield and WUE increases were density > mulching type > hybrid. Grain yield and WUE increased by 20.0% and 3.45 kg ha−1 mm−1 and 12.0% and 2.97 kg ha-1 mm−1 from low to medium density and medium to high density; ET and grain yield and WUE increased simultaneously from low to medium density, however grain yield and WUE improved but ET changed slightly from medium to high. Soil water content of the 0–200 cm layer during growing season was always higher in FMRF than in FMCF, and ET did not differ. FMRF kept more than 50–90 mm soil water in the 0–200 cm during grain filling period. Neither higher grain yield in the FMRF depleted soil water, nor resulted in soil desiccation regardless of the year of precipitation. On the contrary, the FMRF kept much more water into soil layers at corn harvest, and negative effects to soil water balance were not observed. Thus, the package of FMRF combining with close planting and density tolerance hybrids is climate-smart technique for coping with droughts and ensuring corn yield in rainfed areas.

Background Inappropriate disposal of the plastic mulching debris could create macroplastics (MaPs) and microplastics (MiPs) pollution in agricultural soil. Methods To study the effects of farming systems on accumulation and distribution of agricultural plastic debris, research was carried out on two farming systems in Northwest China. Farming in Wutong Village (S1) is characterized by small plots and low-intensity machine tillage while farming in Shihezi (S2) is characterized by large plots and high-intensity machine tillage. In September 2017, we selected six fields in S1, three fields with 6–8 years of continuous plastic mulching (CM) as well as three fields with over 30 years of intermittent mulching (IM). In S2, we selected five cotton fields with 6, 7, 8, 15 and 18 years of continuous mulching. In both regions, MaPs and MiPs from soil surface to 30 cm depth (0–30 cm) were sampled. Results The results showed that in S1, MaPs mass in fields with 6–8 years CM (i.e., 97.4kg·ha−1) were significantly higher than in fields with 30 years IM (i.e., 53.7 kg·ha−1). MaPs in size category of 10–50 cm2 accounted for 46.9% in fields of CM and 44.5% in fields of IM of total collected MaPs number. In S2, MaPs mass ranged from 43.5 kg·ha−1 to 148 kg·ha−1. MaPs in size category of 2–10 cm2 account for 41.1% of total collected MaPs number while 0.25–2 cm2 accounted for 40.6%. MiPs in S1 were mainly detected in fields with over 30 years of intermittent mulching (up to 2,200 particles·kg−1 soil), whereas in S2 were detected in all fields (up to 900 particles·kg−1 soil). The results indicated farming systems could substantially affect the accumulation and distribution of agricultural plastic debris. Continuous plastic mulching could accumulate higher amount of MaPs than intermittent plastic mulching. High-intensity machine tillage could lead to higher fragmentation of MaPs and more severe MiPs pollution. These results suggest that agricultural plastic regulations are needed.

Plastic residues have become a serious environmental problem in areas where agricultural plastic film are used intensively. Although numerous of studies have been done to assess its impacts on soil quality and crop yields, the understanding of meso-plastic particles effects on plant is still limited. In this study, low density polyethylene (PE) and biodegradable plastic (Bio) mulch film were selected to study the effects of meso-plastic debris on soybean germination and plant growth with the accumulation levels of 0%, 0.1%, 0.5% and 1% in soil (w: w, size ranging 0.5–2 cm) by a pot experiment under field condition. Results showed that the germination viability of soybean seeds was reduced to 82.39%, 39.44% and 26.06% in the treatments with 0.1%, 0.5% and 1% added plastic debris compared to the control (CK), respectively, suggesting that plastic residues in soil inhibit the viability of soybean seed germination. The plastic debris had a significant negative effect on plant height and culm diameter during the entire growth stage of soybean. Similarly, the leaf area at harvest was reduced by 1.97%, 6.86% and 11.53% compared to the CK in the treatments with 0.1%, 0.5% and 1% plastic debris addition, respectively. In addition, the total plant biomass under plastic addition was reduced in both the flowering and harvesting stages, compared to the CK. For the different type of plastic residues, plant height, leaf area and root/shoot ratio at group PE were significantly lower than those of groups treated by Bio. In conclusion, PE debris had a greater negative effects on plant height, culm diameter, leaf area and root/shoot ratio while Bio debris mainly showed the adverse effects on germination viability and root biomass especially at the flowering stage. Therefore, further research is required to elaborate plastic particles’ effects on different stages of crops and soil quality.

Plastic film has been intensively used in (semi-)arid agricultural regions, attributing to its great benefits of improving soil productivity and crop yield in China. However, plastic debris, as a consequence of film mulching, remains and accumulates in soil leading to severe soil quality problems, as well as environmental concerns especially the small fragmented particles referred to as microplastics (MPs). Though increasing attention has been aroused for MPs in the aquatic environment, the knowledge of MPs’ behavior and its effects on soil quality is extremely insufficient and urgently needed. In this study, we oriented the benefits of plastic film use, its contribution to agriculture productivity, and the effects of MPs on soil properties and its related soil quality indicators. Admittedly, the increasing trend of using plastic film made by light density of polyethylene would be continued in China, and the pieces of plastic particles would either be persistent and accumulated in soil layers or be slowly aging and degraded. The impacts of MPs on soil quality need more attention due to the limited studies available focusing on its fate and interactions associated with soil ecosystem services and environmental resilience. Although policies and agricultural extending services on plastic film application have been laughed for a few years, alternative materials used for producing environment-friendly film, plastic debris recycling, and solutions on pieced particle removal are the great challenges for sustainable farming. Thus, it is urgent to understand MPs’ effects on soil quality which is crucial for soil-plant system and soil pollution monitoring and prevention.

To identify the ideal harvest time (IHT) for the seed production of XY335 and ZD958, six seed-related traits were evaluated in seeds harvested at 11 harvest stages in 8 environments. Standard germination (SG), accelerated aging germination (AAG) and cold test germination (CTG) were vigor traits; hundred-seed weight (HSW) and seed moisture content (SMC) were physiological traits; and ≥10 °C accumulated temperature from pollination to harvest (AT10ph) was an ecological trait. All the traits were significantly affected by harvest stage. The responses of SG, AAG, CTG and HSW to postponing harvest stage fit quadratic models, while SMC and AT10ph fit linear models. The IHT (indicated by the last date to reach maximum SG, AAG and CTG) were 57.97 DAP and 56.80 DAP for XY335 and ZD958, respectively. SMC and AT10ph at IHT were 33.15% and 1234 °C for XY335, and 34.98% and 1226 °C for ZD958, respectively. The period to reach the maximum HSW was 5 days later than the IHT. Compared to HSW and SMC, AT10ph had a closer relationship to the seed vigor traits. Together with the fact that AT10ph was less affected by environment, these results suggested that AT10ph may be a novel indicator for determining the IHT.

A field experiment was conducted to investigate the effect of long-term (30-year) fertilizer and organic manure treatments on grain yield, soil chemical properties and some microbiological properties of arable soils in Pingliang, Gansu, China. Six treatments were chosen for this work: unfertilized control (CK), nitrogen fertilizer annually (N), nitrogen and phosphorus (P) fertilizers annually (NP), straw plus N added annually and P fertilizer added every second year (NP + S), farmyard manure added annually (FYM), and farmyard manure plus N and P fertilizers added annually (NP + FYM). Mean winter wheat yields for the 20 years ranged from 1.60 Mg ha − 1 for the CK treatment to 4.62 Mg ha − 1 for the NP+FYM treatment. Maize yields for the 8 years averaged 3.40 and 7.66 Mg ha − 1 in the same treatments. The results showed that there was no interaction between farmyard manure and NP fertilizers. Compared with the CK treatment, the average soil organic carbon (SOC) and total nitrogen (TN) content were 2.0 and 3.1%, 1.9 and 13.3%, 32.7 and 24.5%, 23.0 and 19.4%, and 39.9 and 27.6% larger, respectively, for N, NP, FYM, NP + S and NP + FYM. The N only resulted in not only lowering of pH but also deficient of both P and K in the soil. Soil available K declined rapidly without straw or manure additions. The microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) contents increased with the application of nitrogen and phosphorus inorganic fertilizers. However, there was greater increase of these parameters when organic manure was applied along with inorganic fertilizers. Organic manure application also increased soil dehydrogenase, alkaline phosphatases, β-glucosidasen and urease activity significantly. The results indicated that long-term additions of organic manure have the most beneficial effects on grain yield and soil quality among the investigated types of fertilization.

Changes in grain yields and soil organic carbon (SOC) from a 26 y dryland fertilization trial in Pingliang, Gansu, China, were recorded. Cumulative C inputs from straw and root and manure for fertilizer treatments were estimated. Mean wheat (Triticum aestivum L.) yields for the 18 y ranged from 1.72 t ha-1 for the unfertilized plots (CK) to 4.65 t ha-1 for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn (Zea mays L.) yields for the 6 y averaged 2.43 and 5.35 t ha-1 in the same treatments. Yields declined with year except in the CK for wheat. Wheat yields for N only declined with time by 117.8kg ha-1 y -1 that was the highest decrease among all treatments, and that for NP declined by 84.7 kg ha-1 y -1 , similar to the declines of 77.4 kg ha-1 y -1 for the treatment receiving straw and N annually and P every second year (SNP). Likewise, the corn yields declined highly for all treatments, and the declined amounts ranged from 108 to 258kg ha-1 y -1 which was much higher than in wheat. These declined yields were mostly linked to both gradual dry weather and nutrients depletion of the soil. The N only resulted in both P and K deficiency in the soil, and soil N and K negative balances in the NP and MNP were obvious. Soil organic carbon (SOC) in the 0-20 cm soil layer increased with time except in the CK and N treatments, in which SOC remained almost stable. In the MNP and M treatments, 24.7% and 24.0% of the amount of cumulative C input from organic sources remained in the soil as SOC, but 13.7% of the C input from straw and root in the SNP, suggesting manure is more effective in building soil C than straw. Across the 26 y cropping and fertilization, annual soil-C sequestration rates ranged from 0.014 t C ha-1 y -1 for the CK to 0.372 t C ha-1 y -1 for the MNP. We found a strong linear relationship (R 2 = 0.74, p = 0.025) between SOC sequestration and cumulative C input, with C conversion-to-SOC rate of 16.9%, suggesting these dryland soils have not reached an upper limit of C sequestration.

Soil carbonate (SIC) exceeds organic carbon (SOC) greatly in arid lands, thus may be important for carbon sequestration. However, field data for quantifying carbonate accumulation have been lacking. This study aims to improve our understanding of SIC dynamics and its role in carbon sequestration. We analyzed two datasets of SOC and SIC and their 13C compositions , one with over 100 soil samples collected recently from various land uses in the Yanqi Basin, Xinjiang and the other with 18 archived soil samples from a long-term experiment (LTE) in Pingliang, Gansu. The data from the Yanqi Basin showed that SOC had a significant relationship with SIC and pedogenic carbonate (PIC); converting shrub land to cropland increased PIC stock by 5.2 kg C m−2, which was 3.6 times of that in SOC stock. The data from the LTE showed greater accumulation of PIC (21–49 g C m−2 year−1) than SOC (10–39 g C m−2 year−1) over 0–20 cm. Our study points out that intensive cropping in the arid and semi-arid regions leads to an increase in both SOC and PIC. Increasing SOC through straw organic amendments enhances PIC accumulation in the arid cropland of northwestern China.

The wheat- ( Triticum aestivum L.) and corn- ( Zea mays L.) rotation system is important for food security in Northwest China. Grain yield and water-use efficiency [WUE: grain yield/estimated evapotranspiration (ET)] were recorded during a 24-year fertilization trial in Pingliang (Gansu, China). Mean yields of wheat for the 16 years, starting in 1981, ranged from 1.29 Mg ha −1 for unfertilized plots (CK) to 4.71 Mg ha −1 for plots that received manure (M) annually with nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years, starting in 1979, averaged 2.29 and 5.61 Mg ha −1 for the same respective treatments. Whether the years were dry, normal or wet, average grain yields and WUEs for both crops were consistently highest in the MNP and lowest in the CK treatment, and were always lower in the N than in the M treatment and in all others treatments that received N along with P fertilizers. More importantly, WUEs for MNP and for straw along with N annually and P every second year (SNP) were always higher than the other fertilized treatments in dry years. Compared to yield data, coefficients of variance (CV) for WUEs were consistently low for all treatments, suggesting that WUEs were relatively stable from year to year. Yields and WUEs declined over time, except in the CK and MNP treatments for wheat. Declined yields of wheat for the N and M treatments were comparable, and the decline for the NP treatment was similar to that for the SNP treatment. Likewise, corn yields and WUEs declined for all treatments. Grain yields were significantly correlated with ET, with slopes ranging from 0.5 to 1.27 kg m −3 for wheat and from 1.15 to 2.03 kg m −3 for corn. Balanced fertilization and long-term addition of organic material to soil should be encouraged in this region to maximize the use of stored soil water, arrest grain yields decline, and ensure sustainable productivity using this intensive cereal cropping system.

Wheat (Triticum aestivum L.) and corn (Zea mays L.) rotation is important for the region's food security in Northwest China. Grain yield and water-use efficiency (WUE: grain yield/estimated evapotranspiration [ET]) trends, and changes in soil properties during a 24-yr rainfed fertilization experiment in Pingliang, Gansu, China, were recorded. Mean wheat yields for the 16 yr ranged from 1.29 Mg ha⁻¹ for the unfertilized plots (CK) to 4.71 Mg ha⁻¹ for the plots that received manure (M) annually with inorganic N and P fertilizers (MNP). Corn yields for the 6 yr averaged 2.29 and 5.61 Mg ha⁻¹ in the same treatments. Yields and WUEs declined with years except for the CK and MNP treatments for wheat. Wheat yields for the N and M treatments declined about 80 kg ha⁻¹ yr⁻¹, compared with about 60 kg ha⁻¹ yr⁻¹ for the NP treatment and the N plus straw treatment receiving P every second year (SNP). Likewise, the corn yields and WUEs declined significantly for all treatments. Grain yield-ET relationships were linear with slopes ranging from 0.51 to 1.27 kg ha⁻¹ m⁻³ for wheat and 1.15 to 2.03 kg ha⁻¹m⁻³ for corn. Soil organic C (SOC), total N (TN), and total P (TP) gradually increased with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N treatment. Soil available K declined rapidly without straw or manure additions. The greatest SOC increases of about 160 mg kg⁻¹ yr⁻¹ occurred in SNP and MNP treated soils, suggesting that long-term additions of organic materials could increase water-holding capacity that, in return, improves water availability to plants and arrests grain yield declines, and sustains productivity.

Wheat (Triticum aestivum L.) and corn (Zea mays L.) rotation system is important for food security in the Loess Plateau of China. Grain yield and water-use efficiency (WUE: grain yield per unit of water consumed) trends, and changes in soil properties during a 24-year fertilization experiment in Pingliang, Gansu, China, were recorded. Mean yields of wheat for the 16 years started in 1981 ranged from 1.29 t ha−1 for the unfertilized plots (CK) to 4.71 t ha−1 for the plots that received manure (M) annually with inorganic nitrogen (N) and phosphorus (P) fertilizers (MNP). Corn yields for the 6 years started in 1979 averaged 2.29 and 5.61 t ha−1 in the same treatments. Yields and WUEs declined significantly with lapse of time except CK and MNP for wheat. Wheat yields with the N and M declined at rate of 77 and 81 kg ha−1 year−1, but the decline of 57 kg ha−1 year−1 for NP was similar to that of 61 ha−1 year−1 for straw with N annually and P every second year (SNP). Likewise, the corn yields and WUEs declined from 160 to 250 kg ha−1 year−1 and from 0.01 to 0.03 kg m−3 year−1 among treatments, respectively. These declines were likely to loss of soil fertility and gradual dry weather. Yields were significantly correlated with seasonal evapotranspiration with slopes ranging from 0.5 to 1.27 kg m−3 for wheat and from 1.15 to 2.03 kg m−3 for corn. Soil organic carbon (SOC), total N (TN), and total P (TP) gradually built up with time except the CK, in which TN and TP remained unchanged but SOC and available P (AP) decreased. Soil AP decreased in the N. Soil available K declined rapidly without straw or manure. Balanced fertilization should be encouraged to ensure sustainable productivity in this intensive cropping system. The greatest SOC increases of about 160 mg ha−1 year−1 occurred in the SNP and MNP, suggesting that long-term additions of organic materials to soil could increase soil water-holding capacity which, in return, improves water availability to plants and arrests yield declines, and decrease CO2 emission from agricultural soils and sustain land productivity.

Water stress restricts grain yield in the Loess Plateau of China. Two experiments were conducted during three consecutive crop seasons to evaluate benefits of supplemental irrigation from harvested water. Twelve to 48 mm of irrigation was applied at growth stages of corn (Zea mays L.) and winter wheat (Triticum aestivum L.) grown on soil covered with white plastic. Additional 7-yr wheat and 4-yr corn experiments focused on the use of plastic for water efficient use. Irrigation increased grain yield, water use efficiency (WUE), and irrigation water use efficiency (IWUE) for all years. The IWUEs from combined use of the plastic and 12 mm of irrigation were 636 kg m -3 for wheat at jointing stage and 18.05 kg m -3 for corn at V15 stage in a dry year, with IWUE two to six times greater than WUE. Relative to control conditions, plastic applied at seeding increased WUE from 0.77 to 0.98 kg m -3 for wheat and from 1.52 to 1.94 kg m -3 for corn, but greatest available soil water (ASW) and WUE were achieved when plastic was applied during fallow period before seeding. Grain yield-evapotranspiration relationships were linear with regression coefficients of 1.15 kg m -3 for wheat and 4.56 kg m -3 for corn. Most data points from plastic plots were above the regression line while most from the control plots were below the line, indicating increased WUE by the plastic. The ASW at seeding was more important for wheat than corn because sufficient rainfall normally occurs during corn season while the latter portion of wheat season is usually dry.

The effects of long-term (29 years) fertilization on local agro-ecosystems in the Loess Plateau of northwest China, containing a single or combinations of inorganic (Nitrogen, N; Phosphate, P) and organic (Mature, M Straw, S) fertilizer, including N, NP, SNP, M, MNP, and a control. The soil enzymes, including dehydrogenase, urease, alkaline phosphatase, invertase and glomalin, were investigated in three physiological stages (Jointing, Dough, and Maturity) of wheat growth at three depths of the soil profile (0-15, 16-30, 31-45 cm). We found that the application of farmyard manure and straw produced the highest values of soil enzymatic activity, especially a balanced applied treatment of MNP. Enzymatic activity was lowest in the control. Values were generally highest at dough, followed by the jointing and maturity stages, and declined with soil profile depth. The activities of the enzymes investigated here are significantly correlated with each other and are correlated with soil nutrients, in particular with soil organic carbon. Our results suggest that a balanced application of fertilizer nutrients and organic manure (especially those containing P) has positive effects on multiple soil chemical parameters, which in turn enhances enzyme activity. We emphasize the role of organic manure in maintaining soil organic matter and promoting biological activity, as its application can result in a substantial increase in agricultural production and can be sustainable for many years.

The effects of the long-term inorganic (nitrogen, N; phosphate, P) and organic (manure, M; straw, S) fertilizers/managemenet individually and in combinations (N, NP, SNP, M, and MNP) on soil microbial activity were investigated in a wheat field on the Loess Plateau, China. Microcalorimetry was used to determine microbial activity under different treatments. Nearly 30 years of consecutive fertilization has altered the culturable population of soil bacteria and fungi, the highest ones were detected in the treatments of manure and MNP, followed by the NP and SNP treatments. The microbial growth rate constant (μ/h−1) was significantly greater in the MNP treatment than all the other treatments. The total heat exchange values (Q/J) were the highest in the MNP and NP treatments, which were significantly different from the N and M treatments. The peak height (P t/μW) were significantly higher in MNP and NP treatments than in the remaining treatments. The peak time values (t p/h) among the MNP, NP, SNP and M, N and CK treatments were significantly different. In general, comparing with control, soil microbial activity was much higher in MNP, NP and SNP treatments, all including the phosphate fertilizer. Our results showed that the application of inorganic fertilizer and organic manure have positive effects on multiple soil chemical parameters, soil microorganism abundance and activity, and hence crop yield.

An understanding of the dynamics of soil organic carbon (SOC) as affected by farming practices is imperative for maintaining soil productivity and mitigating global warming. The objectives of this study were to investigate the effects of long-term fertilization on SOC and SOC fractions for the whole soil profile (0-100 cm) in northwest China. The study was initiated in 1979 in Gansu, China and included six treatments: unfertilized control (CK), nitrogen fertilizer (N), nitrogen and phosphorus (P) fertilizers (NP), straw plus N and P fertilizers (NP+S), farmyard manure (FYM), and farmyard manure plus N and P fertilizers (NP+FYM). Results showed that SOC concentration in the 0-20 cm soil layer increased with time except in the CK and N treatments. Long-term fertilization significantly influenced SOC concentrations and storage to 60 cm depth. Below 60 cm, SOC concentrations and storages were statistically not significant between all treatments. The concentration of SOC at different depths in 0-60 cm soil profile was higher under NP+FYM follow by under NP+S, compared to under CK. The SOC storage in 0-60 cm in NP+FYM, NP+S, FYM and NP treatments were increased by 41.3%, 32.9%, 28.1% and 17.9%, respectively, as compared to the CK treatment. Organic manure plus inorganic fertilizer application also increased labile soil organic carbon pools in 0-60 cm depth. The average concentration of particulate organic carbon (POC), dissolved organic carbon (DOC) and microbial biomass carbon (MBC) in organic manure plus inorganic fertilizer treatments (NP+S and NP+FYM) in 0-60 cm depth were increased by 64.9-91.9%, 42.5-56.9%, and 74.7-99.4%, respectively, over the CK treatment. The POC, MBC and DOC concentrations increased linearly with increasing SOC content. These results indicate that long-term additions of organic manure have the most beneficial effects in building carbon pools among the investigated types of fertilization.