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Soil Olsen P level has a major influence on crop yield, efficient P utilization, and soil fertility. In this study, the optimum Olsen P range was determined from long-term (1990–2012) field experiments in three typical soil types of China under single cropping of maize or double cropping of maize and wheat. The critical soil Olsen P value for crop yield was evaluated using three different models, and the relationships among P use efficiency (PUE), Olsen P, and total P were analyzed. The agronomic critical soil Olsen P values obtained from the three models for the neutral soil of Gongzhuling and the calcareous soil of Zhengzhou were similar; however, the values from the linear-linear and linear-plateau models for both maize and wheat were substantially lower than those from the Mitscherlich model for the acidic soil of Qiyang. The PUE response change rates (linear equation slopes) under different soil Olsen P levels were small, indicating slight or no changes in the PUE as the soil Olsen P increased in all three soils. A comparison of the Olsen P levels that achieved the maximal PUE with the agronomic critical values derived from the three models indicated that the linear-plateau model exhibited the best performance. The regression equation coefficients of Olsen P response to total P decreased as follows: Zhengzhou (73 mg g−1) > Qiyang (65 mg g−1) > Gongzhuling (55 mg g−1). The Olsen P level increased as the total P increased, which may result in a decrease in PUE. To achieve a relatively high crop yield, PUE, and soil fertility, the optimum Olsen P range should be 13–40, 10–40, and 29–40 mg kg−1 at Gongzhuling, Zhengzhou, and Qiyang, respectively.

Soil microbes play essential roles in the biogeochemical processes of organic carbon and nutrient cycling. Many studies have reported various short-term effects of fertilization on soil microbes. However, less is known about the effects of longterm fertilization regimes on the rhizosphere. Therefore, the objective of this study was to explore how the soil microbial communities in the rhizosphere respond to different long-term fertilization strategies. Based on a 21-year field treatment experiment in Guizhou, China, we extracted phospholipid fatty acids (PLFAs) to determine the microbial community structure in both the non-rhizosphere (NR) and rhizosphere (R). Six treatments were included: no fertilizer (CK), mineral nitrogen fertilizer (N), N with potassium (NK), phosphorus with K (PK), NPK, and NPK combined with manure (MNPK). The results showed that total PLFAs under unbalanced mineral fertilization (N, NK and PK) were decreased by 45% on average in the NR compared with CK, whereas MNPK increased fungi and G– bacteria abundance significantly in both the NR (by 33 and 23%) and R (by 15 and 20%), respectively. In addition, all microbial groups in the R under these treatments (N, NK and PK) were significantly increased relative to those in the NR, except for the ratio of F/B and G+/G–, which might be due to the high nutrient availability in the R. Soil pH and SOC significantly regulated the soil microbial community and structure, explaining 51 and 20% of the variation in the NR, respectively. However, the rhizosphere microbial community structure was only significantly affected by soil pH (31%). We concluded that the soil microbial community in the NR was more strongly affected by long-term fertilization than that in the R due to the rhizosphere effect in the agricultural ecosystem. Rhizosphere nutrient conditions and buffering capacity could help microbial communities resist the change from the long-term fertilization.

Understanding the decomposition dynamics and driving factors of manure in the soil subjected to different reclaimed years could provide theoretical basis to rational utilization of manure and soil fertility improvement in coal mining area. Cattle manure and pig manure were mixed with soils subjected to different reclaimed years (one year, R基于煤矿区不同复垦年限土壤,研究有机肥的分解动态及其驱动因素,可为有机肥合理施用和矿区土壤培肥提供科学依据。本研究以山西煤矿复垦区为试验平台,采用尼龙网袋填埋法,在复垦年限为1年(复垦初期阶段,R

The contribution percentage of inherent soil productivity (CPISP) refers to the ratio of crop yields under no-fertilization versus under conventional fertilization with the same field management. CPISP is a comprehensive measure of soil fertility. This study used 1 086 on-farm trials (from 1984–2013) and 27 long-term field experiments (from 1979–2013) to quantify changes in CPISP. Here, we present CPISP3 values, which reflect the CPISP states during the first three years after site establishment, for a series of sites at different locations in China collected in 1984–1990 (the 1980s), 1996–2000 (the 1990s), and 2004–2013 (the 2000s). The results showed that the average CPISP3 value for three crops (wheat, rice, and maize) was 53.8%. Historically, the CPISP3 in the 1990s (57.5%) was much higher than those in the 1980s (50.3%), and the 2000s (52.0%) (P≤0.05). Long-term no-fertilization caused CPISP levels to gradually decline and then stabilize; for example, in a mono-cropping system with irrigation, the CPISP values in Northwest and Northeast China declined by 4.5 and 4.0%, respectively, each year for the first ten years, but subsequently, the CPISP values stabilized. In contrast, the CPISP for upland crops in double-cropping systems continued to decrease at a rate of 1.1% per year. The CPISP for upland-paddy cropping decreased very slowly (0.07% per year), whereas the CPISP for paddy cropping decreased sharply (3.1% per year, on average) for the first two years and then remained steady during the following years. Therefore, upland crops in double-cropping systems consume the most inherent soil productivity, whereas paddy fields are favourable for maintaining a high level of CPISP. Overall, our results demonstrate a need to further improve China's CPISP3 values to meet growing productivity demands.

The concentration of soil Olsen-P is rapidly increasing in many parts of China, where P budget (P input minus P output) is the main factor influencing soil Olsen-P. Understanding the relationship between soil Olsen-P and P budget is useful in estimating soil Olsen-P content and conducting P management strategies. To address this, a long-term experiment (1991–2011) was performed on a fluvo-aquic soil in Beijing, China, where seven fertilization treatments were used to study the response of soil Olsen-P to P budget. The results showed that the relationship between the decrease in soil Olsen-P and P deficit could be simulated by a simple linear model. In treatments without P fertilization (CK, N, and NK), soil Olsen-P decreased by 2.4, 1.9, and 1.4 mg kg–1 for every 100 kg ha–1 of P deficit, respectively. Under conditions of P addition, the relationship between the increase in soil Olsen-P and P surplus could be divided into two stages. When P surplus was lower than the range of 729–884 kg ha–1, soil Olsen-P fluctuated over the course of the experimental period with chemical fertilizers (NP and NPK), and increased by 5.0 and 2.0 mg kg–1, respectively, when treated with chemical fertilizers combined with manure (NPKM and 1.5NPKM) for every 100 kg ha–1 of P surplus. When P surplus was higher than the range of 729–884 kg ha–1, soil Olsen-P increased by 49.0 and 37.0 mg kg–1 in NPKM and 1.5NPKM treatments, respectively, for every 100 kg ha–1 P surplus. The relationship between the increase in soil Olsen-P and P surplus could be simulated by two-segment linear models. The cumulative P budget at the turning point was defined as the “storage threshold” of a fluvo-aquic soil in Beijing, and the storage thresholds under NPKM and 1.5NPKM were 729 and 884 kg ha–1 P for more adsorption sites. According to the critical soil P values (CPVs) and the relationship between soil Olsen-P and P budget, the quantity of P fertilizers for winter wheat could be increased and that of summer maize could be decreased based on the results of treatments in chemical fertilization. Additionally, when chemical fertilizers are combined with manures (NPKM and 1.5NPKM), it could take approximately 9–11 years for soil Olsen-P to decrease to the critical soil P values of crops grown in the absence of P fertilizer.

This study investigated the water resource potential for bioenergy production from sweet sorghum (Sorghum bicolor (L.)) in Northern China according to the distribution of water resources, climate conditions and the total water consumption of bioenergy based on sweet sorghum, which consisted of blue water, green water and grey water. At a case study site in Inner Mongolia, simulation with a plant phenological model was used to determine whether sweet sorghum could reach the harvestable stage for sugar juice production. The blue water in the agricultural phase was estimated according to the potential crop evapotranspiration (ETc), the drought sensitivity of sweet sorghum in different stages and the precipitation during the growing season. The results showed that the irrigation water was significantly different among the districts, ranging from 730 to 5500 m3/ha and 2060 to 6680 m3/ha for early-maturing and late-maturing varieties, respectively. To avoid the water pressure level to be exacerbated and the severe reallocation of water resources resulting in negative effects on other sectors, the maximal annual water withdrawal was set to not surpass the upper threshold of water stress level of 40%. That makes the maximum area for the production of sweet sorghum cannot exceed 1.95 × 104 ha, representing only 0.24% of the total marginal land area in Inner Mongolia. However, the economic benefits of bioenergy production from sweet sorghum would be negative due to the high labour input. Therefore, not only the availability of marginal land, the climate conditions and local water resources but also the improvement of mechanisation and agricultural production techniques should be considered to attain the sustainable development of bioenergy production and address global energy and environmental crises.

Purpose: Understanding the soil nitrogen (N) mineralization potential (N0) and crop N availability during the growing season is essential for improving nitrogen use efficiency (NUE) and preventing over-fertilization, which lead to negative environmental impacts. Methods: Five black soils with different levels of fertility were selected in Northeast China. The N0 and kinetics of these soils were estimated through laboratory experiments at different incubation temperatures (15, 25, and 35 °C). N mineralization dynamics were simulated using field soil temperature according to the incubation results. Moreover, the N uptake dynamics of maize were simulated according to the literature. Results: Compared with the very low-fertility soils, the cumulative mineralized nitrogen increased under all incubation temperatures (15, 25, and 35 °C), by 48–136%, 8–61%, and 24–59%, respectively, in the medium- and high-fertility soils. The highest N0 values (96.90, 115.31, and 121.33 mg/kg at the three different temperatures) were recorded in the very high-fertility soils. The soil N mineralization dynamics and N uptake of maize in the growing season were highly consistent over time, although the soil N supply could not meet the maize growth requirements. The higher the soil fertility, the lower the N fertilizer requirement. Conclusions: Different fertilizer strategies were developed based on the cumulative mineralized N, N uptake by maize, and NUE in soils with different fertility levels. We suggested a reduction of 50–65 kg N/ha in N fertilizer in the two highest fertility soils. This study provided basic data to reduce chemical N fertilizer to improve NUE and reduce negative environmental impacts.

Applications of manure and chemical fertilizers can significantly modulate the bacterial communities in soil, but the effects on the soil antibiotic resistome and the underlying mechanisms remain largely unclear. In the present study, antibiotic resistance genes (ARGs) and bacterial communities were characterized using high-throughput quantitative PCR and Illumina HiSeq sequencing, respectively, in soils from a long-term (25 years) field experiment. Treatments included no fertilizers (control), chemical fertilizers (NPK), NPK with straw return (NPKS), pig manure (M), and M with chemical fertilizers (NPKM). Both NPK and NPKS decreased soil pH and induced a substantial shift in the bacterial communities, but had only moderate effect on the ARG diversity and abundance. The effect of straw return was hindered by the dominant influence of NPK. In comparison, additions of pig manure (M and NPKM) maintained the diversity of bacterial community and significantly influenced the ARG profiles by introducing extra ARGs from pig manure and boosting the soil indigenous ARG members. Manured soils harboured clusters of ARGs and transposase genes which were relatively independent of bacterial phylogenetic lineages, suggesting a strong co-occurrence of ARGs in soil bacteria which may result from horizontal gene transfers (HGT). Our results indicate the importance of HGT in the maintenance of ARG composition in agricultural soils, especially those receiving long-term manure applications.

Black soil is one of the most precious soil resources on earth because it has abundant carbon stocks and a relatively high production capacity. However, decreasing organic matter after land reclamation, and the effects of long-term inputs of organic carbon have made it less fertile black soil in Northeast China. Straw return could be an effective method for improving soil organic carbon (SOC) sequestration in black soils. The objective of this study was to evaluate whether straw return effectively increases SOC sequestration. Long-term field experiments were conducted at three sites in Northeast China with varying latitudes and SOC densities. Study plots were subjected to three treatments: no fertilization (CK); inorganic fertilization (NPK); and NPK plus straw return (NPKS). The results showed that the SOC stocks resulting from NPKS treatment were 4.0 and 5.7% higher than those from NPK treatment at two sites, but straw return did not significantly affect the SOC stocks at the third site. Furthermore, at higher SOC densities, the NPKS treatment resulted in significantly higher soil carbon sequestration rates (CSR) than the NPK treatment. The equilibrium value of the CSR for the NPKS treatment equated to cultivation times of 17, 11, and 8 years at the different sites. Straw return did not significantly increase the SOC stocks in regions with low SOC densities, but did enhance the C pool in regions with high SOC densities. These results show that there is strong regional variation in the effects of straw return on the SOC stocks in black soil in Northeast China. Additional cultivations and fertilization practices should be used when straw return is considered as an approach for the long-term improvement of the soil organic carbon pool.

The combined use of chemical and organic fertilizers is considered a good method to sustain high crop yield and enhance soil organic carbon (SOC), but it is still unclear when and to what extent chemical fertilizers could be replaced by organic fertilizers. We selected a long-term soil fertility experiment in Gongzhuling, Northeast China Plain to examine the temporal dynamics of crop yield and SOC in response to chemical nitrogen, phosphorus, and potassium (NPK) fertilizers and manure, applied both individually and in combination, over the course of three decades (1980–2010). We aimed to test 1) which fertilizer application is the best for increasing both maize yield and SOC in this region, and 2) whether chemical fertilizers can be replaced by manure to maintain high maize yield and enhance SOC, and if so, when this replacement should be implemented. We observed that NPK fertilizers induced a considerable increase in maize yield in the first 12 years after the initiation of the experiment, but manure addition did not. In the following years, the addition of both NPK fertilizers and manure led to an increase in maize yield. SOC increased considerably in treatments with manure but remained the same or even declined with NPK treatments. The increase in maize yield induced by NPK fertilizers alone declined greatly with increasing SOC, whereas the combination of NPK and manure resulted in high maize yield and a remarkable improvement in SOC stock. Based on these results we suggested that NPK fertilizers could be at least partially replaced by manure to sustain high maize yield after SOC stock has reached 41.96 Mg C ha −1 in the Northeast China Plain and highly recommend the combined application of chemical fertilizers and manure (i.e., 60 Mg ha −1 ).

Long-term use of artificial fertiliser has a significant impact on soil organic carbon (SOC). We used physical-chemical fractionation methods to assess the impact of long-term (26years) fertilisation in a maize cropping system developed on Brown Earth in Northeast China. Plot treatments consisted of control (CK); nitrogen (N) fertiliser (N2); low-level organic manure combined with inorganic N and phosphorus (P) fertiliser (M1N1P1); medium-level organic manure combined with inorganic N fertiliser (M2N2); and high-level organic manure combined with inorganic N and P fertiliser (M4N2P1). Our objectives were to (1) determine the contents of and variations in the SOC fractions; (2) explore the relationship between total SOC and its fractions. In treatments involving organic manure (M1N1P1, M2N2, and M4N2P1), total SOC and physically protected microaggregate (μagg) and μagg occluded particulate organic carbon (iPOC) contents increased by 9.9-58.9%, 1.3-34.7%, 29.5-127.9% relative to control, respectively. But there no significant differences (P>0.05) were detected for the chemically, physically-chemically, and physically-biochemically protected fractions among the M1N1P1, M2N2, and M4N2P1 treatments. Regression analysis revealed that there was a linear positive correlation between SOC and the unprotected coarse particulate organic carbon (cPOC), physically protected μagg, and iPOC fractions (P

Carbon sequestration in agricultural soils is a complex process controlled by farming practices, climate and some other environment factors. Since purple soils are unique in China and used as the main cropland in Sichuan Basin of China, it is of great importance to study and understand the impacts of different fertilizer amendments on soil organic carbon (SOC) changes with time. A research was carried out to investigate the relationship between soil carbon sequestration and organic carbon input as affected by different fertilizer treatments at two long-term rice-based cropping system experiments set up in early 1980s. Each experiment consisted of six identical treatments, including (1) no fertilizer (CK), (2) nitrogen and phosphorus fertilizers (NP), (3) nitrogen, phosphorus and potassium fertilizers (NPK), (4) fresh pig manure (M), (5) nitrogen and phosphorus fertilizers plus manure (MNP), and (6) nitrogen, phosphorus and potassium fertilizers plus manure (MNPK). The results showed that annual harvestable carbon biomass was the highest in the treatment of MNPK, followed by MNP and NPK, then M and NP, and the lowest in CK. Most of fertilizer treatments resulted in a significant gain in SOC ranging from 6.48 to 29.13% compared with the CK, and raised soil carbon sequestration rate to 0.10–0.53 t ha−1 yr−1. Especially, addition of manure on the basis of mineral fertilizers was very conducive to SOC maintenance in this soil. SOC content and soil carbon sequestration rate under balanced fertilizer treatments (NPK and MNPK) in the calcareous purple soil (Suining) were higher than that in the acid purple soil (Leshan). But carbon conversion rate at Leshan was 11.00%, almost 1.5 times of that (7.80%) at Suining. Significant linear correlations between soil carbon sequestration and carbon input were observed at both sites, signifying that the purple soil was not carbon-saturated and still had considerable potential to sequestrate more carbon.

This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates (>2, 1–2, 0.5–1, 0.25–0.5, and 0.25 mm) and mean weight diameter (MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Fallow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in all aggregate sizes by 17–62% and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Fallow decreased SOC and TN contents in all aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in all aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in >0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in >1 mm macro-aggregates, and Fallow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at all tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in all aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in all aggregates in loess soil subjected to dryland farming.

The improvement of soil productivity depends on a rational input of water and nutrients, optimal field management, and the increase of basic soil productivity (BSP). In this study, BSP is defined as the productive capacity of a farmland soil with its own physical and chemical properties for a specific crop season under local field management. Based on 19-yr data of the long-term agronomic experiments (1989–2008) on a fluvo-aquic soil in Zhengzhou, Henan Province, China, the decision support system for agrotechnology transfer (DSSAT ver. 4.0) crop growth model was used to simulate yields by BSP of winter wheat (Triticum aestivium L.) and summer maize (Zea mays L.) to examine the relationship between BSP and soil organic carbon (SOC) under long-term fertilization. Five treatments were included: (1) no fertilization (control), (2) nitrogen, phosphorus and potassium fertilizers (NPK), (3) NPK plus manure (NPKM), (4) 1.5 times of NPKM (1.5NPKM), and (5) NPK plus straw (NPKS). After 19 yr of treatments, the SOC stock increased 16.7, 44.2, 69.9, and 25.2% under the NPK, NPKM, 1.5NPKM, and NPKS, respectively, compared to the initial value. Among various nutrient factors affecting contribution percentage of BSP to winter wheat and summer maize, SOC was a major affecting factor for BSP in the fluvo-aquic soil. There were significant positive correlations between SOC stock and yields by BSP of winter wheat and summer maize (P

In order to reveal the impact of various fertilization strategies on carbon (C) and nitrogen (N) accumulation and allocation in corn ( Zea mays L.), corn was grown in the fields where continuous fertilization management had been lasted about 18 years at two sites located in Central and Northeast China (Zhengzhou and Gongzhuling), and biomass C and N contents in different organs of corn at harvest were analyzed. The fertilization treatments included non-fertilizer (control), chemical fertilizers of either nitrogen (N), or nitrogen and phosphorus (NP), or phosphorus and potassium (PK), or nitrogen, phosphorus and potassium (NPK), NPK plus manure (NPKM), 150% of the NPKM (1.5NPKM), and NPK plus straw (NPKS). The results showed that accumulated C in aboveground ranged from 2 550–5 630 kg ha −1 in the control treatment to 9 300–9 610 kg ha −1 in the NPKM treatment, of which 57–67% and 43–50% were allocated in the non-grain organs, respectively. Accumulated N in aboveground ranged from 44.8–55.2 kg ha– 1 in the control treatment to 211–222 kg ha −1 in the NPKM treatment, of which 35–48% and 33–44% were allocated in the non-grain parts, respectively. C allocated to stem and leaf for the PK treatment was 65 and 49% higher than that for the NPKM treatment at the both sites, respectively, while N allocated to the organs for the PK treatment was 18 and 6% higher than that for the NPKM treatment, respectively. This study demonstrated that responses of C and N allocation in corn to fertilization strategies were different, and C allocation was more sensitive to fertilization treatments than N allocation in the area.

The available methods to determine the ultimate displacement of the building structures have been put forward, and the disadvantages of the methods are analyzed. According to the seismic design theory based on displacement of structures and reinforcement standard of Chinese ancient architecture, which refers to the modern structural engineering requirements, the ultimate displacement of the timber structure on Chinese ancient buildings, which is under the obvious P-∆ second-order effects, has been studied. The ultimate displacement and the drift ratio limit value of different axial compression ratio are determined by the experiments and Theoretical calculation. The results of the study of ultimate displacement can provide the technical support for the rehabilitation of the ancient timber buildings.

The same two straight mortise-tennon joints in the base of melon-column (SJ for short) and penetrated mortise-tennon joints (PJ for short) were made with related rules. Relations of moment-rotation, length of the tenon pulled out-rotation and failure modes were got through monotonic loading test. Experimental study showed the main damage type of SJ was pulling out, while two damage types of PJ were bending damage and transverse tearing failure respectively. When under the action of bending moment, the resisting torque of SJ was synthesized by vertical load of columns, while that of PJ was mainly synthesized by local compresssive stress and friction on upper and lower surface of the tennon. In addition, the pulling size of tennons was associated with the heigth of tenon and relative rotation of beam and column.

Automatic test case generation has been a hotspot and a difficult problem in the software testing, Accurately and efficiently generate test cases can improve the efficiency of software testing. Java programs have many characteristics such as encapsulation, inheritance, polymorphism and so on, it is convenient for software design and development, but to bring automated testing some difficulties. This article on the Java program of automatic test case generation method is studied and presents a framework for automatic generation of test cases. With this framework, test case suite will be generated quickly and accurately. Experimental results show that automatic Java test case generation framework can quickly and accurately generate test cases , reduce labor costs and improve efficiency.

Soil organic carbon (SOC) and soil Olsen-P are key soil fertility indexes but information on their relationships is limited particularly under long-term fertilization. We investigated the relationships between SOC and the percentage of soil Olsen-P to total P (PSOPTP) under six different 15-yr (1990–2004) long-term fertilizations at two cropping systems in northern China. These fertilization treatments were (1) unfertilized control (control); (2) chemical nitrogen (N); (3) N plus chemical P (NP); (4) NP plus chemical potassium (NPK); (5) NPK plus animal manure (NPKM) and (6) high NPKM (hNPKM). Compared with their initial values in 1989 at both sites, during the 11th to 15th fertilization years annual mean SOC contents were significantly increased by 39.4–47.0% and 58.9–93.9% at Gongzhuling, Jilin Province, and Urumqi, Xinjiang, China, under the two NPKM fertilizations, respectively, while no significant changes under the no-P or chemical P fertilization. During the 11th to 15th fertilization years, annual mean PSOPTP was respectively increased by 2.6–4.2 and 5.8–14.1 times over the initial values under the two chemical P fertilizations and the two NPKM fertilizations, but was unchanged in their initial levels under the two no-P fertilizations at both sites. Over the 15-yr long-term fertilization SOC significantly positively correlated with PSOPTP (r2=0.55–0.79, P

Soil organic carbon (SOC), soil microbial biomass carbon (SMBC) and SMBC quotient (SMBC/SOC, qSMBC) are key indexes of soil biological fertility because of the relationship to soil nutrition supply capacity. Yet it remains unknown how these three indexes change, which limits our understanding about how soil respond to different fertilization practices. Based on a 22-yr (1990–2011) long-term fertilization experiment in northwest China, we investigated the dynamics of SMBC and qSMBC during the growing period of winter wheat, the relationships between the SMBC, qSMBC, soil organic carbon (SOC) concentrations, the carbon input and grain yield of wheat as well. Fertilization treatments were 1) nonfertilization (control); 2) chemical nitrogen plus phosphate plus potassium (NPK); 3) NPK plus animal manure (NPKM); 4) double NPKM (hNPKM) and 5) NPK plus straw (NPKS). Results showed that the SMBC and qSMBC were significantly different among returning, jointing, flowering and harvest stages of wheat under long-term fertilization. And the largest values were observed in the flowering stage. Values for SMBC and qSMBC ranged from 37.5 to 106.0 mg kg−1 and 0.41 to 0.61%, respectively. The mean value rank of SMBC during the whole growing period of wheat was hNPKM>NPKM>NPKS>CK>NPK. But there were no statistically significant differences between hNPKM and NPKM, or between CK and NPK. The order for qSMBC was NPKS>NPKM>CK>hNPKM>NPK. These results indicated that NPKS significantly increased the ratio of SMBC to SOC, i.e., qSMBC, compared with NPK fertilizer or other two NPKM fertilizations. Significant linear relationships were observed between the annual carbon input and SOC (P

Long-term fertilization experiment provides the platform for understanding the proton budgets in nitrogen transformations of agricultural ecosystems. We analyzed the historical (1990–2005) observations on four agricultural long-term experiments in China (Changping, Chongqing, Gongzhuling and Qiyang) under four different fertilizations, i.e., no-fertilizer (control), sole chemical nitrogen fertilizer (FN), sole chemical phosphorous and potassium fertilizers (FPK) and chemical nitrogen, phosphorous and potassium fertilizers (FNPK). The significant decline in topsoil pH was caused not only by chemical N fertilization (0.29 and 0.89 ΔpH at Gongzhuling and Qiyang, respectively) but also by chemical PK fertilization (0.59 ΔpH at Gongzhuling). The enhancement of available nutrients in the topsoil due to long-term direct nutrients supply with chemical fertilizers was in the descending order of available P (168–599%)>available K (16–189%)>available N (9–33%). The relative rate of soil pH decline was lower under long-term judicious chemical fertilization (−0.036–0.034 ΔpH yr−1) than that under long-term sole N or PK fertilization (0.016–0.086 ΔpH yr−1). Long-term judicious chemical fertilization with N, P and K elements decreases the nutritional limitation to normal crop growth, under which more N output was distributed in biomass removal rather than the loss via nitrate leaching. We concluded that the N distribution percentage of nitrate leaching to biomass removal might be a suitable indicator to the sensitivity of agricultural ecosystems to acid inputs.

The characteristics of soil pH and exchangeable acidity in soil profile under different vegetation types were studied in hilly red soil regions of southern Hunan Province, China. The soil samples from red soil profiles within 0-100 cm depth at fertilized plots and unfertilized plots were collected and analyzed to understand the profile distribution of soil pH and exchangeable acidity. The results showed that, pH in 0-60 cm soil from the fertilized plots decreased as the following sequence: citrus orchardArachis hypogaea fieldtea garden. As for exchangeable acidity content, the sequence was A. hypogaea field ≤ citrus orchardtea garden. After tea tree and A. hypogaea were planted for long time, acidification occurred in surface soil (0-40 cm), compared with the deep soil (60-100 cm), and soil pH decreased by 0.55 and 0.17 respectively, but such changes did not occur in citrus orchard. Soil pH in 0-40 cm soil from the natural recovery vegetation unfertilized plots decreased as the following sequence: Imperata cylindrica landCastanea mollissima gardenPinus elliottii forest ≥ Loropetalum chinensis forest. As for exchangeable acidity content, the sequence was L cylindrica landC. mollissima gardenL. chinensis forest ≤ P. elliottii forest. Soil pH in surface soil (0-20 cm) from natural forest plots, secondary forest and Camellia oleifera forest were significantly lower than that from P. massoniana forest, decreased by 0.34 and 0.20 respectively. For exchangeable acidity content in 0-20 cm soil from natural forest plot, P. massoniana forest and secondary forest were significantly lower than C. oleifera forest. Compared with bare land, surface soil acidification in unfertilized plots except I. cylindrica land had been accelerated, and the natural secondary forest was the most serious among them, with surface soil pH decreasing by 0.52. However, the pH increased in deep soils from unfertilized plots except natural secondary forest, and I. cylindrica land was the most obvious among them, with soil pH increasing by 0.43. The effects of fertilization and vegetation type on pH and exchangeable acidity decreased with the increasing soil depth from all plots.

The outer-wall thermal insulation system has been wide used in civil engineering as an effective energy-saving measure. At present, the organic flammable thermal insulation materials such as EPS and XPS are used in outer-wall thermal insulation system in China, which leads to great fire damage probably. The rock-wool is described in detail on its merits such as good thermal insulation performance, good sound insulation performance, light weight, low thermal conductivity coefficient, incombustibility, innocuity and stable chemical capability. Two popular outer-wall external thermal insulation systems are introduced. The construction sequence of the outer-wall external thermal insulation system with rock-wool slabs, mortar and thin layer plastering technology is described.

Soil physical properties are important indicators of the potential for agricultural production. Our objective was to evaluate the effects of long-term inputs of green manures on physical properties of a reddish paddy soil (Fe-Typic Hapli-Stagnic Anthrosols) under a double cropping system. The common cropping pattern before the study was early-late rice-fallow (winter). The field treatments included rice-rice-fallow (R-R-WF), rice-rice-rape (R-R-RP), rice-rice-Chinese milk vetch (R-R-MV), and rice-rice-ryegrass (R-R-RG). The rape, Chinese milk vetch and ryegrass were all incorporated as green manures 15 d before early rice transplanting during the following year. The soil bulk density in all green manure treatments was significantly reduced compared with the winter fallow treatment. Soil porosity with green manure applications was significantly higher than that under the winter fallow. The green manure treatments had higher 0.25–5 mm water stable aggregates and aggregates stabilities in the plow layer (0–15 cm depth) compared with the fallow treatment. The mean weight diameter (MWD) and normalized mean weight diameter (NMWD) of aggregates in the green manure treatment were larger than that with the winter fallow. Soil given green manure retained both a higher water holding capacity in the plow layer soil, and a larger volume of moisture at all matric potentials (−10, −33 and −100 kPa). We conclude that the management of double-rice fields in southern central China should be encouraged to use green manures along with chemical fertilizers to increase SOC content, improve soil physical properties and soil fertility.

Impacts of 33-yr of application of S-containing and Cl-containing chemical fertilizers on rice (Oryza sativa L.) yield and its components were investigated in a red paddy field experiment, south China. The treatments included: 1) adding 302 kg SO42−-S ha−1 yr−1 with application of (NH4)2SO4, K2SO4, and calcium superphosphate (SO42−); 2) adding 56 kg SO42−-S and 176 kg Cl ha−1 yr−1 with application of urea, calcium superphosphate, and KCl (Cl−+SO42−); 3) adding 516 kg Cl ha−1 yr−1 with application of NH4Cl, KCl, and KH2PO4 (Cl−). Under each treatment, the applied N, P, and K nutrients were controlled at conventional rates of 150 kg N ha−1 yr−1, 75 kg P2O5 ha−1 yr−1, 225 kg K2O ha−1 yr−1, respectively. Under the S-containing fertilizer application, soil SO42−-S content showed a first increasing then decreasing trend with years, and was significantly negatively correlated with annual rice yield. Average annual yield significantly declined in an order of Cl−, Cl−+SO42−, and SO42−. Under the Cl− treatment, soil SO42−-S content was maintained at about 26.5 mg kg−1, not showing deficiency. From 1990 to 2000, rice yield declined rapidly under the SO42− treatment, and was significantly lower than that under the Cl− treatment. After then, there was no significant difference in yield among the treatments. Our results demonstrated that long-term application of S-containing fertilizer could result in excessive accumulation of SO42−-S in the red paddy soils of south China, therefore producing a certain threat to rice growth. The Cl-containing fertilizer could be relatively safe.

Sustainable potassium (K) management at different soil sites requires understanding the relationships between crop productivity and long-term K fertilizations on a regional or national scale. We analyzed responses of grain yield of wheat (Triticum aestivum L.) and maize (Zea mays L.), K efficiency, and partial balance (difference between K input through fertilizer and K output in the aboveground biomass) during 15- (1990-2005) or 18-year (1990-2008) K fertilizations at five distinctive agroecological zones across China. Compared to the inorganic nitrogen (N) and phosphorus (P) fertilization, the inorganic NPK fertilization significantly increased grain yields of wheat (21%) and maize (16%-72%) at Qiyang and Changping, where soils have low exchangeable and non-exchangeable K contents, but not at Urumqi, Yangling and Zhengzhou, where soils have a high exchangeable and non-exchangeable K and/or low N/K ratio in crop plants. Compared to the inorganic NPK fertilization, the inorganic NPK (30% N) and organic manure (70% N) fertilization (NPKM) increased grain yields of wheat (14%-40%) and maize (9%-61%) at four sites, but not at Zhengzhou. For a productivity of wheat at 2-5 t ha−1 or maize at 3-6 t ha−1, 13-26 or 9-17 kg K ha−1 were required to produce 1.0 t wheat or maize. The NP fertilization resulted in the lowest negative partial K balance and accumulated 52 kg K ha−1 year−1 less than the NPK fertilization, which accumulated 28 kg ha−1 year−1 less K than the NPKM fertilization. A re-evaluation of the site-specific fertilization effects on N/K ratio in crop plants and soil K accumulation under current NPK and NPKM fertilization is urgently needed to increase both crop yield and K use efficiency at different agroecological zones across China.