Intensive Vegetable Cultivation Research Articles

Chemical attributes, bacterial community, and antibiotic resistance genes are affected by intensive use of soil in agro-ecosystems of the Atlantic Forest, Southeastern Brazil.

Soil is one of the largest reservoirs of microbial diversity in nature. Although soil management is vital for agricultural purposes, intensive practices can have a significant impact on fertility, microbial community, and resistome. Thus, the aim of this study was to evaluate the effects of an intensive soil management system on the chemical attributes, composition and structure of prevalent bacterial communities, and presence and abundance of antimicrobial resistance genes (ARGs). The chemical characterization, bacterial diversity and relative abundance of ARGs were evaluated in soils from areas of intensive vegetable cultivation and forests. Results indicate that levels of nutrients and heavy metals were higher in soil samples from cultivated areas. Similarly, greater enrichment and diversity of bacterial genera was detected in agricultural areas. Of the 18 target ARGs evaluated, seven were detected in studied soils. The oprD gene exhibited the highest abundance among the studied genes and was the only one that showed a significantly different prevalence between areas. The oprD gene was identified only from soil of the cultivated areas. The blaSFO, erm(36), oprD and van genes, in addition to the pH, showed greater correlation with in soil of cultivated areas, which in turn exhibited higher contents of nutrients. Thus, in addition to changes in chemical attributes and in the microbial community of the soil, intensive agricultural cultivation systems cause a modification of its resistome, reinforcing the importance of the study of antimicrobial resistance in a One Health approach.

Influence of nutrient, toxic metal and herbicide contents on the soil bacterial communities in tropical vegetable growing areas

The relationship between bacterial diversity and the bioavailability of nutrients, toxic metals and the herbicide oxyfluorfen in a tropical vegetable growing area was evaluated. The study was conducted in a vegetable growing area located in the mountainous region of Rio de Janeiro (Brazil), and samples were collected in areas of vegetable cultivation and areas of environmental reserve. Fertility analyses and determination of the pseudototal levels of toxic metals in the soil samples were performed. The profile of the soil bacterial community was determined by amplification of the 16S rRNA gene and separation by DGGE. The results showed that the levels of toxic metals and elements associated with soil fertility were higher in vegetable production areas. These differences in the physical and chemical characteristics of the soil favored the presence of a greater number of OTUs in the cultivation areas (17.3-27 OTUs) than in the areas of environmental reserve (13-22 OTUs). Therefore, this study demonstrates that the presence of toxic metals and the herbicide oxyfluorfen and the increase in fertility in soils in areas with intensive vegetable cultivation resulting from the intensive management adopted in these areas promotes a differentiation of the bacterial profiles in soils in tropical vegetable growing areas.

Optimizing organic substitution: Balancing carbon sequestration and priming effects of a six-year field experiment for sustainable vegetable production

Organic substitution has been recognized to markedly influence soil organic carbon (SOC) dynamics and carbon sequestration. However, the priming effect can alter SOC mineralization, contingent upon the varying proportions and intensities of mineralization introduced by fresh organic substrates. A comprehensive assessment to pinpoint the organic substitution level in intensive vegetable cultivation remains elusive. Thus, we carried out a 6-year field experiment, following four fertilization treatments at consistent nitrogen levels: solely mineral fertilizer; and organic fertilizers replacing 20 %, 50 %, and 100 % of mineral nitrogen fertilizer. We assessed carbon dioxide emissions derived from various sources, soil properties, nutrient availability, enzyme activity, 13C-phospholipid fatty acid, SOC stability, and nutrient stoichiometries via a 63-day incubation with 13C glucose. Our results showed that different levels of organic substitution significantly affected soil mineralization and priming effect. The microbial community was the primary determinant of priming effect, accounting for 59.4 % of the variation, with gram-positive bacteria (i.e., a15: 0) being instrumental. Moreover, organic fertilizers provided a large amount of labile substrate, diminishing the microbial requirement for enzyme production in SOC decomposition. Notably, 50 % organic substitution consistently outperformed others, consistently yielding 1.17 to 1.29 times more than alternative treatments. Furthermore, this approach exhibited the lowest cumulative priming effect, which declined by 26.9 % to 44.8 %, attributed to enhanced SOC stability. Therefore, a 50 % organic substitution effectively balances carbon sequestration and the priming effect, contributing to sustainable vegetable production. Collectively, our results highlight the importance of appropriate organic substitution rates in promoting carbon sequestration and reducing greenhouse gas emissions for producing higher vegetable yield. Further work should emphasize long-term field evaluations to validate our priming effect determinants and explore the comprehensive impacts on soil health and sustainable agriculture.

GIS-based multicriteria and artificial neural network (ANN) investigation for the assessment of groundwater vulnerability and pollution hazard in the Braga shallow aquifer (Central Tunisia): A critical review of generic and modified DRASTIC models

Groundwater vulnerability and pollution hazard in the Braga shallow aquifer were assessed through an integrated GIS-based multicriteria analysis and Artificial Neural Network (ANN) approach, using DRASTIC and DRASTIC-LU models. The DRASTIC model integrates seven geological parameters. The DRASTIC-LU model includes an eighth parameter in addition to the previous ones. This parameter is the land use that represents the human source of groundwater pollution. The DRASTIC map showed four classes: very low (12.06%), low (81.88%), moderate (5.16%) and high (0.9%), where the vulnerability index ranged between 43 and 159. The DRASTIC-LU vulnerability index ranged between 53 and 204 and showed five classes: very low (3.10%), low (14.06%), moderate (17.11%), high (27.08%) and very high (38.65%). The DRASTIC-LU vulnerability map indicated that the high pollution risk is imposed by the intensive vegetable cultivation and the domestic wastewater. The pollution hazard index (PHI) was calculated based on the ANN modelling, using the land-use as an input and the vulnerability as a hidden layer. The DRASTIC model-based PHI map showed six classes: rare hazard (8.6%), very low (30.97%), low (6.18%), moderate (51.45%), high (2.43%) and very high (0.37%). While, The DRASTIC-LU model-based PHI map (PHILU) showed seven classes: rare hazard (2.91%), very low (11.9%), low (12.33%), moderate (13.78%), high (9.23%), very high (15.46%) and extremely hazardous (34.39%). The validation of these maps indicated that the DRSTIC-LU-based PHI is more reliable as it accurately identifies the hazardous zones.

Improving potential of reactive nitrogen and carbon footprint of intensified greenhouse cucumber-tomato production with optimized drip irrigation with nitrogen reduction strategies

Guaranteeing a robust supply of vegetables is a significant public welfare endeavor. However, the implementation of irrational water and fertilizer regimes in greenhouse vegetable fields (GVF) has resulted in adverse environmental impacts. Therefore, it is crucial to develop water and fertilizer regimes to maintain the productivity of greenhouse vegetables with less carbon (C) and reactive nitrogen (Nr) footprint. A four growing seasons experiment involving the cultivation of cucumbers and tomatoes was conducted in the suburbs of Beijing. The experiment comprised three treatments: flood irrigation with a conventional urea-N application (FN), drip fertigation with a conventional urea-N application (DN), and drip fertigation with a 50% reduction of urea-N application (DRN). The results showed that about 70% of annual N inputs in GVF were surplus, posing a high risk of loss. For the FN treatment, the N budget, Nr loss, Nr footprint per unit of vegetable yield (NrFY), Nr footprint per unit of net return (NrFR), greenhouse gas (GHG) emissions, C footprint per unit of vegetable yield (CFY), C footprint per unit of net return (CFR) were respectively quantified as follows: 1653 kg N ha−1 yr−1, 776 kg N ha−1 yr−1, 4.39 kg N t−1 yr−1, 24.48 kg N ¥10000−1 yr−1, 46548 kg CO2-eq ha−1 yr−1, 262.98 kg CO2-eq t−1 yr−1 and 1467.58 kg CO2-eq ¥10000−1 yr−1. Compared with FN, DN significantly reduced Nr loss (25%), NrFY (24%), NrFR (22%), GHG emissions (6%), CFY (4%), while it increased N surplus (9.7%) and produced lower farmers' net return (¥ 13486 ha−1 yr−1). Concurrently, DRN significantly reduced the N surplus, Nr loss, NrFY and NrFR by ∼35%, decreased the GHG emissions, CFY and CFR by ∼20%, and improved farmers' net return by ¥ 674 ha−1 yr−1 compared to FN treatment. Therefore, this study highlighted that an integrated water and fertilizer regulation strategy (drip irrigation replacing flood irrigation coupled with a 50% reduction in chemical N application) can simultaneously achieve environmental and economic benefits in the context of high N inputs. This contributes to the sustainable development of intensive vegetable cultivation systems.

Interaction between the hydrochemical environment, dissolved organic matter, and microbial communities in groundwater: A case study of a vegetable cultivation area in Huaibei Plain, China

Intensive vegetable planting has a profound impact on the surrounding aquatic environment. The self-purification ability of groundwater is poor, and it is difficult to return groundwater to its original state once polluted. Therefore, it is necessary to clarify the impact of intensive vegetable planting on groundwater. This study selected the groundwater of a typical intensive vegetable planting base in the Huaibei Plain of China as the research object. This work analyzed the content of major ions, the dissolved organic matter (DOM) composition, and the bacterial community structure in groundwater. Redundancy analysis was used to explore the interactions between the major ions, the DOM composition, and the microbial community. The results showed that under the influence of intensive vegetable planting, the F− and NO3−-N contents in groundwater were significantly increased; the excitation–emission matrix combined with parallel factor analysis identified four fluorescent components (C1 and C2 were humus-like components, while C3 and C4 were protein-like components), which mainly consisted of protein-like components. Proteobacteria was the dominant phylum (mean = 69.27 %), followed by Actinobacteriota (mean = 7.25 %) and Firmicutes (mean = 4.02 %), which together explained over 80 % of the total abundance; and TDS, pH, K+, and C3 were the main influencing factors affecting the microbial community structure. This study provides a better understanding of the impact of intensive vegetable cultivation on groundwater.

A tradeoff between denitrification and nitrate leaching into the subsoil in nitrate-rich vegetable soils treated by reductive soil disinfestation

Intensive vegetable cultivation often leads to substantial accumulation of nitrate (NO3−-N) in the topsoil, thus posing serious threat to groundwater safety by NO3−-N leaching and food safety by excessive uptake of NO3−-N by vegetables. Reductive soil disinfestation (RSD) may remove over-accumulated NO3−-N in the topsoil due to its water-saturated, strongly reductive, and carbon-rich characteristics that favor the removal of NO3−-N via denitrification, immobilization, and leaching. However, how RSD affects the fates of NO3−-N of the topsoil in intensive vegetable lands remains largely unknown. Here, a soil column experiment using 15N tracing technique was conducted to quantify the fates of NO3−-N in the topsoil under RSD in six representative intensive vegetable soils in China. The results showed that an average of 99.7% of the added 15NO3−-N in the topsoil was removed by RSD in all intensive vegetable lands. Denitrification in the entire soil profile and leaching of NO3−-N into the subsoil were responsible for 21.8–78.3% and 14.9–68.4% of the removed 15NO3−-N, respectively, whereas microbial NO3−-N immobilization and dissimilatory nitrate reduction to ammonium in the topsoil played a negligible role in removing 15NO3−-N. A tradeoff was found between denitrification and leaching of NO3−-N into the subsoil among the six soils under RSD. The structural equation modeling demonstrated that the positive effects of RSD on topsoil pH, dissolved organic carbon, and bacterial abundance decreased the leaching of NO3−-N into the subsoil by enhancing denitrification. Overall, the results provided the first direct evidence for complete removal of NO3−-N in the topsoil by RSD. Such an evidence has implications for controlling NO3−-N accumulation through implementing RSD in intensive vegetable soils.

Dancers, Mountains, and People in the Fields

Dancers, Mountains, and People in the Fields

Dissemination of blaNDM-5 via IncX3 plasmids in carbapenem-resistant Enterobacteriaceae among humans and in the environment in an intensive vegetable cultivation area in eastern China.

The environment of a large-scale vegetable production area can be exposed to antibiotic residues and antibiotic-resistant bacteria (ARB) via animal manure and irrigation with contaminated water, which can facilitate the dissemination of ARB. However, the occurrence of ARB in plantation areas and their dissemination in this environment remain largely unexplored. In total, 382 samples including those from vegetable (n=106), soil (n=87), well water (n=24), river water (n=20), river sediments (n=20), farmer feces (n=58) and farmer hands (n=67) were collected in 2019 from a large-scale cultivation area in Shandong, China. Selective agar plates were used to screen for carbapenem-resistant Enterobacteriaceae (CRE) and whole-genome sequencing and Southern blotting were used to characterise isolates and mobile genetic elements carrying carbapenem resistance determinants. A total of nine NDM-5-producing isolates of Escherichia coli, Klebsiella pneumoniae, and Citrobacter spp. were identified from environmental sources and human feces, all of which were multidrug-resistant. Single nucleotide polymorphism analysis suggested clonal transmission of carbapenem-resistant Citrobacter sedlakii within greenhouse soils in the area. Eight of the isolates carried closely related or identical IncX3 plasmids carrying blaNDM-5, which were shown to be conjugative via filter mating experiments, indicating the highly transmissible nature of this genetic element. Isolates of E.coli and Citrobacter freundii were detected in the feces of local farm workers and contained similar IncX3 plasmids with blaNDM-5 environmental isolates, suggesting a potential risk of CRE transfer from the work environment to the farm workers. Thus, further research is required to investigate the potential health risks associated with environmental exposure to CRE in vegetable cultivation areas.

Synergistically Mitigating Nitric Oxide Emission by Co-Applications of Biochar and Nitrification Inhibitor in a Tropical Vegetable Soil

Vegetable soils are the hotspots of nitric oxide (NO) emissions from agro-ecosystems due to intensive management. Biochar application has been recommended as an important countermeasure, however, its mitigation efficiency is limited as biochar largely stimulates soil nitrification. Therefore, co-applied with nitrification inhibitor could maximize the mitigation potential of biochar. Herein, an incubation experiment was conducted to investigate the effects of biochar and nitrification inhibitor applied alone or in combination on NO fluxes, mineral nitrogen intensity and the populations of nitrifiers and denitrifiers in a typical tropical soil under intensive vegetable cultivation. Results showed that biochar or nitrification inhibitor alone significantly decreased NO emissions by 41.6% and 43.5%, respectively, and their co-applications decreased it by up to 68.5%. Soil NO 2 − −N intensity, along with gene abundances of AOB- amoA and nirK were significantly and positively correlated with cumulative NO emissions. Nitrification inhibitor weakened the stimulating effects of biochar on AOB- amoA and total comammox- amoA gene abundances, as well as NO 3 − −N intensity, thus weakening nitrification-driven NO production. Biochar increased qnorB abundance in soils following nitrification inhibitor addition, thereby promoting NO consumption during denitrification. Moreover, biochar or nitrification inhibitor alone decreased nirK gene abundance and NO 2 − −N intensity and these reductions become greater with their co-applications. The present study highlights that co-applications of biochar and nitrification inhibitor can achieve a higher potential to decrease NO emissions from vegetable soil, which should be further verified in the field considering the complex environment conditions in tropical regions.

Emerging Medium-Scale Tenant Farming, Gig Economies, and the COVID-19 Disruption: The Case of Commercial Vegetable Clusters in Ethiopia.

Driven by the fast spread of private irrigation pumps, there has been a rapid expansion of intensive vegetable cultivation in the central Rift Valley in Ethiopia, making it the most important commercial vegetable production cluster in the country. Supporting that “quiet revolution” has been an inflow of migrant laborers—paid through daily, monthly, or piecemeal contracts, with few employment benefits attached to them—and a gig economy as widely used contractors organize, among others, mechanized land preparation, the digging of wells and ponds, seedling propagation, and loading of trucks. Almost 60% of the irrigated area is cultivated by medium-scale tenant farmers relying on short-term rental contracts. It seems that gig economies characterized by flexible contract arrangements implemented by outside contractors, which are increasingly fueling sophisticated sectors in developed countries, are important in these commercial agrarian settings in Africa as well. We further find that the COVID-19 pandemic has led to significant disruptions of this model, as seen by more limited access to services and the unavailability or high price increases in factor markets, especially for labor, and large but heterogenous price changes in output markets.

ENRICHMENT AND BIOAVAILABILITY OF TOXIC ELEMENTS IN INTENSIVE VEGETABLE PRODUCTION AREAS1

ABSTRACT Vegetable cultivation stands out for intensive use of agricultural inputs due to high nutritional requirements of plants within a short period and their high susceptibility to pests and diseases. This study aimed to identify the main factors responsible for changes in pseudo-total and bioavailable contents of Cd, Cu, Cr, Mn, Ni, Pb, and Zn in soils under intensive vegetable cultivation. Soil samples were collected from 146 sites in Petrópolis (RJ), Brazil, in 2017. The samples were collected at a depth of 0-20 cm in family farm systems during vegetable production period. Pseudo-total contents of toxic elements were determined by the EPA 3050B method. Geochemical fractionation procedure was used based on the BCR method. Pollution indices were also calculated. In general, vegetable producing areas presented low contamination by Cu, Zn, Pb, Mn, and Ni, except for Cd, which showed severe contamination. In areas with the lowest slopes, most of the toxic elements showed increasing contents, reflecting relief influence. Overall, inadequate soil management, intensive application of phosphate, potassium, and organic fertilization, and relief were the most influencing parameters on the enrichment and bioavailability of toxic elements in the soil.

Long-term changes in organic matter stocks and quality in an Oxisol under intensive vegetable cultivation

Changes in carbon (C) and nitrogen (N) reserves reflect the impacts of land use and management. The objective was to evaluate the changes in organic matter stocks and quality in an Oxisol under intensive vegetable cultivation in the Brazilian Cerrado region. Four areas were selected: one under Cerrado vegetation (CV) and three under vegetable production with 15 (VG15), 20 (VG20) and 30 (VG30) years of cultivation. Soil samples were collected for the determination of total C (TC) and total N (TN) in soil organic matter fractions and the biochemical composition of particulate organic matter (POM) and mineral-associated organic matter (MOM). The smallest C stocks were observed on VG30, whereas the CV area had the highest values. The TN stocks were similar across treatments. The levels of labile C decreased with cultivation time. Increases and reductions in carbohydrate and lignin ratios in POM and MOM occurred in VG15 and VG20, respectively, with POM being more sensitive to changes in land use. There was greater similarity between VG15 and VG20, but differences between CV and VG30. There was a correlation between higher labile reserves (labile C and carbohydrates) and areas with shorter land use and between Cmic and agricultural use for 30 years. There was also a negative correlation between soil nutrients and the total and MOM C and N contents as well as the MOM carbohydrate levels, and there was also a negative correlation between Cmic and TC. The intensive use of Oxisols promoted a reduction in soil organic matter stocks and altered their quality.

Factors Influencing the Adoption of Good Agricultural Practices and Export Decision of Thailand’s Vegetable Farmers

This research identified and investigated the factors influencing the adoption of good agricultural practices (GAP) and the decision making of small-scale asparagus and sweet corn farmers in Thailand to produce for export. In the study, a total of 147 vegetable farming households (66 and 81 asparagus and sweet corn growers, respectively) were randomly selected from areas with intensive vegetable cultivation. The binary logistic regression was used to analyze the information collected from this survey. The results revealed that the income variable is the most influential factor in the GAP adoption by participating vegetable farmers and that the location factor exerts the most influence over the growers’ export decision. Also, it is felt that to effectively increase the GAP adoption rate among the Thai vegetable growers, the exporters and relevant government agencies could make GAP certification compulsory.

Aerated Irrigation and Pruning Residue Biochar on N2O Emission, Yield and Ion Uptake of Komatsuna

After irrigation in intensive vegetable cultivation, the soil is filled with water leading to reduced oxygen content of the soil air which will affect vegetable growth and soil N2O emission. In this study, the effect of aerated irrigation and residue biochar on soil N2O emission, yield, and ion uptake of komatsuna grown in Andosol was explored. The experiment included four treatments; control (tap water irrigation), aerated water irrigation, pruning residue biochar with tap water irrigation, and a combination of aerated irrigation and biochar. The results showed that aerated irrigation had no effect on plant growth, but it also increased N2O emission by 12.3% for several days after planting. Plant ion uptake was not affected by aerated irrigation. Biochar amendment increased shoot dry weight and significantly reduced soil N2O emission by 27.9% compared with the control. Plant uptake of N and K also increased with biochar. This study showed that pruning residue biochar has the potential to mitigate N2O emission while increasing vegetable growth and plant nutrient uptake. However, the study soil, Andosol, already has high soil porosity with low bulk density. Thus, further injection of air through irrigation showed no effect on plant growth but increased N2O emission, hence soil aeration was not a limiting factor in Andosol.

Effects of 3,4-dimethylpyrazole phosphate (DMPP) on the abundance of ammonia oxidizers and denitrifiers in two different intensive vegetable cultivation soils

Nitrification and denitrification in the N cycle are affected by various ammonia oxidizers and denitrifying microbes in intensive vegetable cultivation soils, but our current understanding of the effect these microbes have on N2O emissions is limited. The nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP), acts by slowing nitrification and is used to improve fertilizer use efficiency and reduce N losses from agricultural systems; however, its effects on nitrifier and denitrifier activities in intensive vegetable cultivation soils are unknown. In this study, we measured the impacts of DMPP on N2O emissions, ammonia oxidizers, and denitrifying microbes in two intensive vegetable cultivation soils: one that had been cultivated for a short term (1 year) and one that had been cultivated over a longer term (29 years). The quantitative PCR technique was used in this study. Three treatments, including control (no fertilizer), urea alone, and urea with DMPP, were included for each soil. The application rates of urea and DMPP were 1800 kg ha−1 and 0.5% of the urea-N application rate. The application of N significantly increased N2O emissions in both soils. The abundance of ammonia-oxidizing bacteria (AOB) increased significantly with high rate of N fertilizer application in both soils. Conversely, there was no change in the growth rate of ammonia-oxidizing archaea (AOA) in response to the applied urea despite the presence of larger numbers of AOA in these soils. This suggests AOB may play a greater role than AOA in the nitrification process, and N2O emission in intensive vegetable cultivation soils. The application of DMPP significantly reduced soil NO3−-N content and N2O emission, and delayed ammonia oxidation. It greatly reduced AOB abundance, but not AOA abundance. Moreover, the presence of DMPP was correlated with a significant decrease in the abundance of nitrite reductase (nirS and nirK) genes. Long-term intensive vegetable cultivation with heavy N fertilization altered AOB and nirS abundance. In vegetable cultivation soils with high N levels, DMPP can be effective in mitigating N2O emissions by directly inhibiting both ammonia oxidizing and denitrifying microbes.

The Use of Slow-Release Fertilizers as a Part of Optimization of Celeriac Production Technology

Abstract The aim of this study was to assess the possibility of using slow-release fertilizers under intensive vegetable cultivation. To achieve the set research objective, a field experiment was set up in 2017, where slow-release fertilizer (NPK (%) 20-10-10+4MgO) was applied. The experiment comprised three levels of fertilization with the use of slow-release fertilizers, the control without fertilization, and the control fertilized with conventional fertilizers. The slow-release fertilizer was applied directly under each plant and in rows – approximately 8 cm below the root level. The designed systems were evaluated based on the size of commercial yield, productivity index, agronomic efficiency index, removal efficiency index, and physiological efficiency index. The results obtained in the field experiment indicate that the highest plant yield (54.22 Mg of commercial yield∙ha−1) was obtained at the highest dose of slow-release fertilizers (600 kg∙ha−1 applied in rows approximately 8 cm below the root level). In the case of direct fertilization, in the treatment with the highest dose of slow-release fertilizer, a reduction in yield was observed. The best results, in terms of equalizing the mass of individual roots, were obtained under conventional fertilization. The most favorable value of the productivity index was obtained in the variant where 400 kg∙ha−1 slow-release fertilizer was applied directly, while in the case of row application the best results were obtained at the dose of 600 kg∙ha−1. Celeriac fertilization with slow-release fertilizers under root may result in producing a yield of bigger differences in root mass, compared to conventional fertilization system.

Effect of long-term intensive vegetable and corn cultivation with inorganic fertilizer on soil properties in mountain agriculture region

Effect of long-term intensive vegetable and corn cultivation with inorganic fertilizer on soil properties in mountain agriculture region

Effect of long-term intensive vegetable and corn cultivation with inorganic fertilizer on soil properties in mountain agriculture region

Effect of long-term intensive vegetable and corn cultivation with inorganic fertilizer on soil properties in mountain agriculture region

Soil nitrate accumulation and leaching to groundwater during the entire vegetable phase following conversion from paddy rice

Large amounts of farmland have been converted from traditional cereal cropping to intensive vegetable cropping in China, creating environmental risks. Previous studies utilized several methods of estimating nitrate accumulation in soil and leaching to groundwater under intensive vegetable cultivation, such as comparing intensive cropping to non-intensive cropping, or investigating the seasonal dynamics of soil nitrates in the short term, such as 1 or 2 years. This study tried to utilize a different method, considering the effects of total nitrogen (N) input during the whole vegetable cropping phase (up to 9 years) after conversion from traditional cereal cropping on soil and groundwater. A large-scale investigation was performed in the study area. Vegetable, soil, and groundwater samples were collected from 22 fields. Results showed that soil nitrate was significantly correlated with total N input from chemical fertilizer during the whole vegetable cropping phase, and groundwater nitrate was significantly correlated with soil nitrate. Nitrate concentration in 45 % of wells exceeded the drinking water maximum contaminant level, 10 mg L−1. These results suggest that soil nitrate accumulation in the area resulted from long-term application of large amounts of N chemical fertilizer, and not from manure. Furthermore, high irrigation levels caused the accumulated nitrate in soil to leach into the groundwater, resulting in nitrate contamination of the groundwater.