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Organic manure application is an important measure for high yield and good quality vegetable production, whereas organic manure is also a main source of residual antibiotic in soils. A 3-yr experiment was conducted on a fluvo-aguic soil in Tianjin of northern China. The objective of this study was to investigate the effects of different fertilization patterns on yield of six-season vegetables with celery and tomato rotation, and dynamic change of tetracyclines residues in the soil during the sixth growing season (tomato season). The field experiment comprised six treatments depending on the proportion of nitrogen of each type of fertilizer: 4/4 CN (CN, nitrogen in chemical fertilizer), ¾ CN+¼ MN (MN, nitrogen in pig manure), 2/4 CN+2/4 MN, ¼ CN+¾ MN, 2/4 CN+¼ MN+¼ SN (SN, nitrogen in corn straw), and CF (conventional fertilization, the amounts of nitrogen application were 943 and 912 kg N ha−1 for celery and tomato season, respectively). In addition to CF treatment, the amount of nitrogen application in other treatments was greatly reduced and equal (450 and 450 kg N ha−1 for celery and tomato season, respectively). Results showed that the combined application of ¾ CN+¼ MN achieved the highest yield and economic benefit in the first four seasons, but addition of straw (2/4 CN+¼ MN+¼ SN treatment) performed better in the subsequent two seasons, and the average yields of 2/4 CN+¼ MN+¼ SN treatment were respectively higher by 9.9 and 12.8% than those of 4/4 CN treatment, and by 5.6 and 10.5% than those of CF treatment. The residual chlortetracycline (CTC) in manure-amended soil for three consecutive years increased along with the increase of applied amount of pig manure. Under the same amount of pig manure application, content of CTC in straw-amended soil was obviously decreased compared with no straw-amended soil (¾ CN+¼ MN treatment), and averagely decreased by 41.9% for four sampling periods in the sixth season. Addition of crop straw facilitated the degradation of CTC in manure-amended soil. As a whole, the conventional fertilization was not the desirable pattern based on yield, economic benefit and environment, the optimal fertilization pattern with the highest yield and profit and the least soil chlortetracycline residue was the treatment of 2/4 CN+¼ MN+¼ SN under this experimental condition.

DSSAT (Decision Support System for Agrotechnology Transfer) -CERES-Maize was employed to characterize maize yield and nitrogen dynamics in a 50-year maize production study at Woodslee, Ontario, Canada. The treatments selected for evaluation included continuous maize/corn with fertilization (CC-F) and continuous maize/corn without fertilization (CC-NF) treatments. The results showed that the DSSAT model could simulate yield of CC-F more precisely than that of CC-NF. The simulated cumulative nitrate loss from CC-F treatment from 1998 to 2000 was consistent with the actual measured value. For CC-NF, The DSSAT model overestimated the cumulative nitrate loss.

Crop models can be useful tools for optimizing fertilizer management for a targeted crop yield while minimizing nutrient losses. In this paper, the parameters of the decision support system for agrotechnology transfer (DSSAT)-CERES-Maize were optimized using a new method to provide a better simulation of maize ( Zea mays L.) growth and N uptake in response to different nitrogen application rates. Field data were collected from a 5 yr field experiment (2006-2010) on a Black soil ( Typic hapludoll ) in Gongzhuling, Jilin Province, Northeast China. After cultivar calibration, the CERES-Maize model was able to simulate aboveground biomass and crop yield of in the evaluation data set ( n-RMSE =5.0-14.6%), but the model still over-estimated aboveground N uptake (i.e., with E values from −4.4 to −21.3 kg N ha −1 ). By analyzing DSSAT equation, N stress coefficient for changes in concentration with growth stage ( CTCNP2 ) is related to N uptake. Further sensitivity analysis of the CTCNP2 showed that the DSSAT model simulated maize nitrogen uptake more precisely after the CTCNP2 coefficient was adjusted to the field site condition. The results indicated that in addition to calibrating 6 coefficients of maize cultivars, radiation use efficiency ( RUE ), growing degree days for emergence ( GDDE ), N stress coefficient, CTCNP2 , and soil fertility factor ( SLPF ) also need to be calibrated in order to simulate aboveground biomass, yield and N uptake correctly. Independent validation was conducted using 2008-2010 experiments and the good agreement between the simulated and the measured results indicates that the DSSAT CERES-Maize model could be a useful tool for predicting maize production in Northeast China.

Agricultural land around the world is often potassium (K) deficient, and decreasing soil K availability is a global challenge for grain producers. In China, negative K budgets are ubiquitous and K depletion is accelerating. Previous studies have mainly focused on the effect of insufficient K fertilizer on single soil types and cropping systems but have not evaluated the effects of balanced fertilizer application on K budgets. In this study, soil K budgets of grain producing soils and the effects of K fertilizer application on crops under different cropping systems and soil types were evaluated from 1992 to 2006. Two treatments each at nine locations in North China were replicated four times, four plots received nitrogen (N) and phosphorus (P) fertilizer application exclusively, and the other four plots received N, P, and K fertilizer application. Basic soil properties, available K, slowly available K, crop rotations, crop K absorption, and yield were monitored and evaluated and K budgets and K use efficiencies were calculated. Average annual K absorption by crops with K fertilizer application was 230.2 kg ha−1 K2O, and the average annual deficit was 46.8 kg ha−1 K2O. Long-term application of K fertilizer increased available soil K on all nine sites by an average of 35.7 mg kg−1. Annual K absorption by crops averaged 99.0 kg ha−1 in the northeast region, 181.2 kg ha−1 in the north-central region, and 220.9 kg ha−1 in the northwest region. Annual K fertilizer use efficiency in the northeast (39.9%) and north-central (38.8%) regions were higher than in the northwest (17.8%). Correlations between annual K budgets and K use efficiency with fertilizer application, crop rotation, and soil type were weak. High spatial variability and low correlation between variables is a result of the complex mechanisms of K cycling. Research directions are proposed which would contribute to a better understanding of these mechanisms and processes and how they affect agronomic and economic objectives.

Soil testing is widely adopted as an essential diagnostic tool for identifying soil nutrient factors that limit sustained crop production. A systematic approach for rapid soil testing and fertilizer recommendation has been introduced and widely used in China by Agro Services International (ASI), USA. To verify the usefulness and reliability of the ASI method in soil testing and fertilizer recommendation in comparison with other commonly used traditional soil testing methods, 294 soil samples from major agricultural regions and soil types in China with a wide range of soil pH, from 5.1 to 8.9, were taken and analyzed for available phosphorus (P) and potassium (K) by the ASI multielement extraction solution and selected traditional methods, Olsen extractant for P, ammonium acetate (NH4OAc) extractant for K, and multielement extractant Mehlich 3 for P and K. Also, 46 soils were selected from northern China regions for a greenhouse trial with sorghum seedlings to determine if the soil testing values correlate...

To study the mechanism of potassium (K) application on improvement of maize resistance to stalk rot at cellular level, scanning electron microscope and transmission electron microscope were used to observe the effect of K on the ultrastructure of maize stalk pith tissue and young root tip cell influenced by K and pathogen. In K deficient treatment, parenchyma cells of stalk pith had abnormal structure, and the cell wall between upper and lower adjacent cell was damaged, resulting in the loss of connections between vascular cells and insufficient supporting capacity. However, an improved K nutrition helped to keep a quite tight arrangement of root cell with thick cell wall, and prevent the invasion of pathogen effectively. Moreover, K treated root cell had abundant golgi apparatus, which could excrete large amount of secretions to degrade mycelium. Papillary and highly electronic intensity dot were accumulated at the invading point to prevent the development of the mycelium. Improved K nutrition could increase the resistant ability of maize plant to stalk rot, through keeping cell structure stability, preventing the expansion of intracellular space to reduce the chances of pathogen invasions, and through reinforcing cell wall and formation of intercellular and intracellular material to restrict further development of pathogen in host cell.

Potash resources in China are very scarce. It is especially important to correctly evaluate the potential potassium‐supplying power of soils in northern China in order to use soil potassium sufficiently and potash fertilizer properly. Regional differences in crop yield responses to long‐term potassium application in northern China were determined in this study. Twenty‐five representative soil samples from 13 provinces, municipalities, and autonomous regions of major agricultural regions in northern China were collected from the surface layer (0–20 cm) before crop seeding in 1993. A soil potassium‐depletion study was carried out in a pot experiment with successive planting of corn seedlings for 10 harvests in the 25 soils. Since 1993, field trials on wheat and corn response to long‐term potassium application were conducted at the fixed sites of HLJ‐SC (Shuangcheng of Heilongjiang), JL‐LFZ (Liufangzi of Jilin), HB‐XJ (Xinji of Hebei), SX‐LF (Linfen of Shanxi), QH‐NKY (Nongkeyuan of Qinghai), and XJ‐CJ (Chan...

A pot experiment was conducted to determine the effects of potassium (K) application on volatile compounds, taste compounds, and firmness of fresh tomato fruits. Each pot was filled with 8 kg of clean sand. The experiment consisted of six K application rates with 0, 1.25, 2.5, 5.0, 10.0, and 20.0 mmol K L−1 in the nutrient solution. Volatile compounds, soluble sugars, soluble solids, titratable acidity, and firmness of fresh tomato fruits were measured. The results show that the concentrations of 3-methylbutanal, 1-penten-3-one, hexanal, cis-3-hexenal, 2-methyl-4-pentenal, trans-2-hexenal, 2E-4E-hexadienal, 6-methyl-5-hepten-2-one, phenylacetaldehyde, phenylethanol, soluble sugars, and soluble solids tended to increase at first and then decrease between 0 to 10.0 mmol K L−1. K application rate obtaining the highest values of the concentrations ranged from 1.4 to 3.0 mmol K L−1, with the exception of cis-3-hexenal (1.1 mmol K L−1), phenylacetaldehyde (4.5 mmol K L−1), and phenylethanol (4.8 mmol K...

To increase fertilizer use efficiency (FUE) and to minimize its negative impact on environment have been the focal points in the world for a long time. It is very important to increase FUE in China for its relatively low FUE and serious losses of nutrients. Recent advances of the technologies to increase FUE are reviewed in this article. These include site-specific and real-time nitrogen management, non-destructive quick test of the nitrogen status of plants, new types of slow release and controlled release fertilizers, site-specific nutrient management, and use of urease inhibitor and nitrification inhibitor to decrease nitrogen losses. Future outlook in technologies related to FUE improvement is also discussed.

The combinative effects of applied zinc (Zn) and soil moisture on the plant growth, Zn uptake, and the metabolism of reactive oxygen species (ROS) in maize (Zea mays L.) plants were examined through two pot experiments under greenhouse conditions. Maize variety Zhongdan 9409 was used. In experiment 1, maize plants were grown in cumulic cinnamon soil with five Zn treatments (0, 3.0, 9.0, 27.0, and 81.0 mg Zn kg^(-1) soil). Three treatments of soil moisture including serious drought, mild drought, and adequate water supply were set at 30-35%, 40-45%, and 70-75% (w/w) of soil saturated water content, respectively. Soil saturated water content was 36% (w/w). The dry matter weights of shoots were enhanced by Zn application and adequate water supply. There was no apparent difference in plant growth among Zn application rates from 3.0 to 81.0 mg Zn kg^(-1) soil. The increases of plant growth and Zn uptake due to Zn application were found more significant under well-watered condition than under drying condition. In experiment 2, two levels of Zn (0 and 5.0 mg Zn kg^(-1) soil) and soil moisture regimen (40-45% and 70-75% of soil saturated water content, respectively) were set. Zn deficiency or water stress resulted in higher concentrations of O2(superscript -), and malondiadehyde in the first fully expanded leaves. Zn deficiency lowered the activity of superoxide dismutase (SOD, EC 1.15.1.1) in leaves. Drought stress increased SOD activity in leaves regardless of Zn supply. The activity of guaiacol peroxidase (POD, EC 1.11.1.11) was found to be enhanced by Zn supply only in well-watered leaves. Zinc deficiency or water stress had little effect on the activity of catalase (CAT, EC 1.11.1.6). The higher ROS level in early maize leaves due to water stress seemed not to be alleviated or lowered partially by Zn application. However, Zn fertilizer was recommended to apply to maize plants irrigated or supplied with adequate water, otherwise Zn deficiency would reduce the water use for plant biomass production.

A pot experiment was conducted to determine the effects of N application on volatile compounds, taste compounds, and firmness of fresh tomato fruits. Each pot was filled with 8 kg of clean sand. The experiment consisted of six nitrogen (N)-application rates with 0, 2.25, 4.50, 9.00, 18.00, and 36.00 mmol N L–1 in the nutrient solution. Volatile compounds, soluble sugars, soluble solids, titratable acidity, and firmness of fresh tomato fruits were measured. The results show that increasing N application increased the concentrations of 1-penten-3-one, hexanal, cis-3-hexenal, 2-methyl-4-pentenal, trans-2-hexenal, 6-methyl-5-hepten-2-one, titratable acidity, soluble sugars, and soluble solids. By contrast, increasing N supply decreased the concentration of phenylacetaldehyde and first increased and then decreased the concentrations of 2E–4E-hexadienal and the firmness of fresh tomato fruits. Close relationships between the concentration of various volatile compounds, titratable acidity, soluble sugars, and soluble solids were found. However, concentrations of these flavor compounds were very poorly correlated with fruit firmness. Based on contributions of these compounds to tomato flavor, we assume that moderate high N supply improves tomato flavor, whereas excessive N supply can deteriorate it.

This study was conducted to determine status of heavy metals in agricultural soils under different patterns of land use. A total of 38, 40 and 45 soil samples for bare vegetable field, greenhouse vegetable field, and grain crop field were respectively taken from surface layer (0-20 cm) from selected experimental areas away from suburbs of ten counties (or districts or cities) in four provinces or municipalities of Huabei plain in north China. Information of crop production history, including varieties, rotation systems and fertilizer use, at the corresponding sampling sites was surveyed. Soil total Cu, Zn, Cd, Pb, Cr, As and Hg were measured. The results showed that the contents of total Cu, Zn, Cd, Pb, Cr, As, and Hg in the soil samples, especially soil total Cu and Zn contents, were higher in the bare vegetable field and the greenhouse vegetable field than that in the grain crop field. Long-term use of excessive chemical fertilizers and organic manures in the bare vegetable field and the greenhouse vegetable field contributed to the accumulation of Cu, Zn, and other heavy metals in the soils. The contents of total Cu, Zn, and other heavy metals in soils increased with increasing vegetable production history of the research areas. In comparison with the grain crop field, the comprehensive pollution indices of the seven soil heavy metals and the single-factor pollution indices of soil Zn, Cu, Cd, Cr, and Hg based on the second criterion of Environmental Quality Standard for Soils were significantly higher in the bare vegetable field and the greenhouse vegetable field. Soils from the greenhouse vegetable field were slightly contaminated according to the comprehensive pollution index, and soils from the bare vegetable field and the grain crop field were at the warning heavy metal pollution level. The soils were contaminated with Cd according to the single-factor pollution index. The Cd pollution was relatively more serious in the bare vegetable field and the greenhouse vegetable field than that in the grain crop field. The soils selected with different land use patterns were not contaminated with Zn, Cu, Pb, Cr, As and Hg.

Based on the data from China Agriculture Yearbook 2006 and other documents, the amounts of crop straws and of the excreta from human, livestock, and poultry in China in 2005 were estimated, with the potential and the environmental risk of their nutrient resources analyzed. In 2005, the total amount of crop straws in this country was 643 million tons, and that of the excreta from human, livestock, and poultry was 4625 million tons. The amounts of N, P2O5, and K2O from the straws and the excreta were 28.24, 12.82, and 29.48 million tons, being 1.08, 0.86, and 4.56 times of the inputs from chemical fertilizers in the same year, respectively. There was a great regional difference in the distribution of the organic manures nutrient resources. The total amount of N, P2O5, and K2O in the excreta was more than 4 million tons in Henan, Shandong, and Sichuan provinces, but less in Beijing, Tianjin, Shanghai, and northwest China, while the total amount of these nutrients in crop straws was more than 1.5 million tons in Henan and Shandong provinces, the main grain production areas, but less in northwest China. The per unit farmland load of N, P2O5, and K2O from the excreta was the highest (787.26 kg x hm(-2)) in Beijing, followed by in Tianjin (515.31 kg x hm(-2)) and Shanghai (505.35 kg x hm(-2)), where the environmental risk could be more serious.

Laboratory and greenhouse research was conducted to study effects of soil properties on the availability of native and applied B in 14 Virginia soils. Boron absorption could be described by the Langmuir equation in 12 of the 14 soils, and maximum B adsorption (Vmax) in these 12 soils ranged from 3.3 to 26.5 mg kg−1. A multiple regression equation, −19.3+3.51 pH+0.048 clay content, accounted for 89.6% of the variation in Vmax for the 12 soils. Curvilinear relationships (α=0.01) occurred between B in corn (Zea mays L.) tissue from native B and hot-water soluble B, mannitol exchangeable B, and NH4-acetate and Mehlich III extractable B. Among these four procedures, mannitol exchangeable B correlated most closely (r=0.923) with B in corn tissue from native B. From 0.4 to 13.5% of the applied B was absorbed by corn plants and translocated to shoots. Curvilinear relationships (α=0.01) occurred between B in corn tissue from applied B and soil clay content, NH4-oxalate extractable Al and Fe, and acidified NH2OH·HCl extractable Mn. It is evident from these relationships that soil clay and oxyhydroxides of Al, Fe, and Mn have an affinity to adsorb B in somewhat unavailable forms.