Irrigation has more influence than fertilization on leaching water quality and the potential environmental risk in excessively fertilized vegetable soils

Characterization of indigenous Durio species from Sarawak, Borneo: relationships between chemical composition and sensory attributes

Sarawak, Borneo, harbours 16 unique Durio species, half of which are edible, with only Durio zibethinus widely cultivated. Despite their nutritional and economic significance to the rural communities in Sarawak, the lesser-known indigenous durians remain underrepresented in the scientific literature while facing the risk of extinction in the wild. Thus, the aim of this study was to conduct comprehensive chemical analyses of these wild edible durians, offering insights into their nutritional and sensory taste attributes. The edible part was separated at optimal ripeness, and the samples were subjected to further analysis. Wild edible durian genotypes exhibit varied characteristics, even within the same species. The majority of wild durians are characterized by a sugar composition consisting predominantly of sucrose, constituting 67.38-96.96%, except for the red-fleshed Durio graveolens renowned for its low total sugar content (0.49 ± 0.17 g per 100 g). Despite its bland taste, this species possessed significantly greater fat (14.50 ± 0.16%) and fibre (12.30 ± 0.14%) content. Durio dulcis exhibited a significantly greater carbohydrate content (29.37-30.60%), and its intense smell was attributed to its low protein content (2.03-2.04%). Indigenous durians offer substantial percentages of daily mineral intake, with 100 g servings providing approximately 15.71-26.80% of potassium, 71.72-86.52% of phosphorus, 9.33-27.31% of magnesium, and sufficient trace minerals. The vibrant flesh colours of yellow-, orange- and red-fleshed Durio graveolens and Durio kutejensis show high levels of ascorbic acid (31.41-61.56 mg 100 g-1), carotenoids (976.36-2627.18 µg 100 g-1) and antioxidant properties, while Durio dulcis and Durio oxleyanus, despite their dull flesh, contained high phenolic (67.95-74.77 mg GAE 100 g-1) and flavonoid (8.71-13.81 QE mg 100 g-1) levels. These endeavours provide a deeper understanding of the nutritional richness of wild edible durians, thereby supporting commercialization and conservation efforts.

Effects of Bacillus subtilis on Cucumber Seedling Growth and Photosynthetic System under Different Potassium Ion Levels

Potassium deficiency is one of the important factors restricting cucumber growth and development. This experiment mainly explored the effect of Bacillus subtilis (B. subtilis) on cucumber seedling growth and the photosynthetic system under different potassium levels, and the rhizosphere bacteria (PGPR) that promote plant growth were used to solubilize potassium in soil, providing theoretical support for a further investigation of the effect of biological bacteria fertilizer on cucumber growth and potassium absorption. "Xinjin No. 4" was used as the test material for the pot experiment, and a two-factor experiment was designed. The first factor was potassium application treatment, and the second factor was bacterial application treatment. The effects of different treatments on cucumber seedling growth, photosynthetic characteristics, root morphology, and chlorophyll fluorescence parameters were studied. The results showed that potassium and B. subtilis had obvious promotion effects on the cucumber seedling growth and the photosynthesis of leaves. Compared with the blank control, the B. subtilis treatment had obvious effects on the cucumber seedling height, stem diameter, leaf area, total root length, total root surface area, total root volume, branch number, crossing number, gs, WUE, Ci, and A; the dry weight of the shoot and root increased significantly (p ≤ 0.05). Potassium application could significantly promote cucumber growth, and the effect of B. subtilis and potassium application was greater than that of potassium application alone, and the best effect was when 0.2 g/pot and B. subtilis were applied. In conclusion, potassium combined with B. subtilis could enhance the photosynthesis of cucumber leaves and promote the growth of cucumber.

Large effect of phosphate-solubilizing bacteria on the growth and gene expression of Salix spp. at low phosphorus levels

Phosphorus is one of the most important nutrients required for plant growth and development. However, owing to its low availability in the soil, phosphorus is also one of the most difficult elements for plants to acquire. Phosphorus released into the soil from bedrock quickly becomes unavailable to plants, forming poorly soluble complexes. Phosphate-solubilizing bacteria (PSB) can solubilize unavailable phosphorus-containing compounds into forms in which phosphorus is readily available, thus promoting plant growth. In this study, two willow species, Salix dasyclados cv. Loden and Salix schwerinii × Salix viminalis cv. Tora, were inoculated with two selected bacterial strains, Pantoea agglomerans and Paenibacillus spp., to evaluate the plant growth parameters and changes in gene expression in the presence of different concentrations of tricalcium phosphate: 0 mM (NP), 1 mM (LP), and 2 mM (HP). Inoculation with PSB increased root, shoot and leaf biomass, and for the HP treatment, significant changes in growth patterns were observed. However, the growth responses to plant treatments tested depended on the willow species. Analysis of the leaf transcriptomes of the phosphate-solubilizing bacterium-inoculated plants showed a large variation in gene expression between the two willow species. For the Tora willow species, upregulation of genes was observed, particularly for those involved in pathways related to photosynthesis, and this effect was strongly influenced by bacterial phosphate solubilization. The Loden willow species was characterized by a general downregulation of genes involved in pathway activity that included ion transport, transcription regulation and chromosomes. The results obtained in this study provide an improved understanding of the dynamics of Salix growth and gene expression under the influence of PSB, contributing to an increase in yield and phosphorus-use efficiency.

Combination of Bacillus and Low Fertigation Input Promoted the Growth and Productivity of Chinese Cabbage and Enriched Beneficial Rhizosphere Bacteria Lechevalieria

Long-term overfertilization increases soil salinity and disease occurrence and reduces crop yield. Integrated application of microbial agents with low fertigation input might be a sustainable and cost-effective strategy. Herein, the promoting effects of Bacillus velezensis B006 on the growth of Chinese cabbage under different fertigation conditions in field trials were studied and the underlying mechanisms were revealed. In comparison with normal fertigation (water potential of -30 kPa and soluble N, P, K of 29.75, 8.26, 21.48 Kg hm-2) without B006 application, the combination of B. velezensis B006 and reduced fertigation input (-50 kPa and N, P, K of 11.75, 3.26, 6.48 Kg hm-2) promoted cabbage growth and root development, restrained the occurrence of soft rot disease, and improved the yield. High-performance liquid chromatography (HPLC) analyses indicated that B006 application promoted the production of indole-3-acetic acid and salicylic acid in cabbage roots, which are closely related to plant growth. Rhizosphere microbiota analyses indicated that the combination of low fertigation input and B006 application promoted the enrichment of Streptomyces, Lechevalieria, Promicromonospora, and Aeromicrobium and the abundance of Lechevalieria was positively correlated with the root length and vitality. This suggested that the integrated application of reduced fertigation and Bacillus is highly efficient to improve soil ecology and productivity and will benefit the sustainable development of crop cultivation in a cost-effective way.

The effect of coconut coir substrate on the yield and nutritional quality of sweet peppers (Capsicum annuum) varieties

The industry standard for estimating the quantity of horticultural produce harvested is crop yield. Producing sufficient amounts of high-quality biochemical ingredients crops can therefore aid in resolving concerns with food security and nutrition. Most producers prefer the use of organic substrate over natural soils when growing crops such as peppers in greenhouses, to ensure that there is a sufficient supply of food all year round. The objective of the study was to determine the effect of coconut coir substrate on the yield and biochemical constituents of peppers varieties grown under greenhouse environment. For two successive seasons [2021 and 2022], two sweet pepper types (Sondela and Ilanga) were cultivated on fertigated coconut coir and loamy soil (control). Fruit number, together with their dry weight and some biochemical constituents, were examined. To evaluate the impact of coconut coir substrate on the growth, yield, and biochemical constituents of different pepper cultivars grown in a greenhouse, dry plant materials and freeze-dried fruit samples were analyzed. Results showed that the coconut coir and variety (Ilanga) treatment combination produced more fruits than other treatments. Biochemical constituents such as vitamins, total phenols, total flavonoids, copper, iron and Zinc were in fruits grown under coir substrate when compared to loamy soil (control). Therefore, farmers are encouraged to grow sweet peppers varieties under coconut coir substrate for better yield, nutritional quality and profit maximisation.

IrrigTool—A New Tool for Determining the Irrigation Rate Based on Evapotranspiration Estimated by the Thornthwaite Equation

In the context of climate change, irrigation has become a must for ensuring crop production because in some regions, the drought episodes became more frequent. The decision to efficiently allocate water resources should be made quickly, based on tools that provide correct information with a low computational effort. Therefore, we propose a new user-friendly tool—IrrigTool—for assessing the irrigation rate considering the precipitation, temperature, evapotranspiration, soil type, and crop. IrrigTool implements the Thornthwaite equations and can be used to identify weakness due to drought stress and as an educational tool. Apart from the computation, it provides a graphical representation of the results and possible comparisons of the output for two locations. The application is built in Microsoft Excel for graphics and Visual Basic VBA. The user does not have programming knowledge to use it. Data on monthly precipitation and temperature data must be introduced in the specified fields, and after pressing the run button, the results are automatically displayed. The article exemplifies the functioning on data series from Romania’s Dobrogea region.

Organic and in-organic fertilizers effects on the performance of tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) grown on soilless medium

The effects of organic fertilizers, based on Tithonia diversifolia, and in-organic fertilizers, based on hydroponics fertilizer, were evaluated on the performance, leaves, and fruit mineral concentrations of tomato (Solanum lycopersicum) and cucumber (Cucumis sativus) plants grown under soilless medium in a screen house. The treatments comprised six levels of liquid organic fertilizer (5, 15, 25, 35, 45, 55 mL), in-organic fertilizer, and a control. Both organic and in-organic fertilizers increased the growth, yield, leaf nutrient concentration, and the mineral contents of tomato and cucumber fruits in comparison with the control. In-organic fertilizer enhanced the performance and mineral concentrations of tomato and cucumber fruits in comparison with organic fertilizer. However, leaf analyses showed that all the essential elements for both tomato and cucumber crops were within the adequate ranges in the organic fertilizer treatments suggesting that this organic fertilizer can be used as an alternative to the expensive and scarce in-organic fertilizer. For organic fertilizer, the highest yield and mineral contents in fruits were attained at doses of 35 mL and 25 mL for tomato and cucumber plants, respectively. At these doses, the fruit weights of tomato and cucumber were increased by 137 and 198%, respectively, in comparison with the control. For a good yield of tomato and cucumber crop with a high fruit mineral content under the soilless medium of coco peat and rice husk, 35 mL and 25 mL of our tested organic fertilizer are recommended.

Effect of Irrigation Water and Organic Fertilizer on Reducing Nitrate Accumulation and Boosting Lettuce Productivity

Accumulation of high level of nitrate (NO3−) in leaves is a serious issue for vegetable crops like lettuce (Lactuca sativa L.). Therefore, this study aimed to limit NO3− level by adjusting the balance between fertilization and irrigation program in lettuce. In a strip plot design with three replicates, lettuce plants were grown under four fertilizer treatments and three irrigation regimes. Three organic fertilizers (biochar, compost and vermicompost), in addition to mineral fertilizer, were used. The irrigation regimes were 60, 80 and 100% of crop evapotranspiration, ETc (ETc60, ETc80, and ETc100). Nitrogen (N), phosphorus (P) potassium (K) and organic matter (OM) in soil as well as yield, N, P, K and NO3− of lettuce were estimated. Findings showed that vermicompost or biochar (with any irrigation regime) as well as compost with irrigation by ETc60 were the effective combinations for increasing K content in soil after harvest. Under irrigation by ETc80 or ETc100, vermicompost or biochar were the efficient treatments for increasing lettuce yield equaling the farmer common practice (ETc100 x mineral fertilizer). Under irrigation by ETc60, mineral fertilizer or vermicompost showed the highest lettuce leaf content of K. Moreover, ETc60 or ETc80 x mineral fertilizer recorded the maximum NO3− content of lettuce leaves. The accumulation of nitrate in lettuce leaves owing to mineral fertilizer reached about 1.24 times than that of organic fertilizers. Compost x ETc80 or ETc100 showed the minimal NO3–N accumulation, hence, high relative reductions in NO3–N accumulation as compared to the common practice (ETc100 x mineral fertilizer) were observed. In conclusion, irrigation by 80% instead of 100% of crop evapotranspiration of organically fertilized lettuce (especially with vermicompost) could be adopted since such practice recorded high lettuce productivity with low NO3− content.

Uranium isotopes in groundwater in Ho Chi Minh City and related issues: Health risks, environmental effects, and mitigation methods

Groundwater is regularly used for many purposes, such as drinking and agricultural irrigation systems. Still, it contains high levels of radionuclides (e.g., ²³⁸U, ²³²Th, and ²²⁶Ra) that are potentially hazardous to humans and the environment. In this study, activity concentrations of uranium isotopes were analyzed in 15 groundwater samples taken from 15 bored wells in Thu Duc district, Ho Chi Minh City, Vietnam. Environmental effects of the irrigation system with groundwater on agricultural soil in the study area were assessed by models. It was found that the activity concentrations of ²³⁸U and ²³⁴U in groundwater samples were in the ranges of (13.5-268.7) mBq l^-1 and (20.2-438.3) mBq l^-1, respectively. The ratio ²³⁴U/²³⁸U values were ranged from 1.12 to 2, with an average value of 1.44. Based on the model prediction, 25 years irrigation with the groundwater can inject 94.8 Bq both uranium isotopes in 1 kg topsoil. For investigated groundwater samples, the proposed removal method using K₂FeO₄ removed 74.28% and 81.04% for ²³⁴U and ²³⁸U, respectively.

Effects of biochar application and irrigation rate on the soil phosphorus leaching risk of fluvisol profiles in open vegetable fields

Biochar application was reported to influence soil phosphorus (P) leaching, but the reports are conflicting, and could be related to soil depth and water management. A field trial of a Wild Cabbage-Chinese Cabbage rotation was used to investigate the effect of biochar application and irrigation volume on P leaching risk in fluvisol soil profiles (0-20 cm, 20-50 cm, 50-100 cm) in the Chaobai River basin. The experiment included two biochar levels [0 (-BC), 30 t/hm2 (+BC)], and two irrigation levels [conventional irrigation (CI) and water-saving irrigation (WSI)]. The irrigation rate of WSI was 80% of CI. The results demonstrated that there was no significant difference in soil leachable P in the soil profiles under the two irrigation volumes, while biochar application tended to increase soil leachable P in the top layer soil (0-20 cm) and subsurface layer soil (20-50 cm) irrespective of the irrigation rate. The average value of the P leaching "change point" in the soil profiles with +BC was significantly higher than that with -BC (0-20 cm: 35.52 mg kg-1 vs. 25.86 mg kg-1; 20-50 cm: 27.61 mg kg-1 vs. 20.02 mg kg-1). Additionally, the P leaching risk was observed in all top layer soil (0-20 cm) irrespective of irrigation rate and biochar application, and the P leaching risk in the subsurface layer (20-50 cm) with +BC was lower than that with -BC, especially under WSI. Therefore, it is recommended that biochar application combined with water-saving irrigation could be used as a measure for controlling soil phosphorus leaching under open field vegetable rotation in the alluvial soil of Chaobai River basin.

Effects of Different Irrigation Management Practices on Potato (Solanum tuberosum L.)

Decisions in irrigation management can greatly impact the overall sustainability of potato production. A field study was conducted in 2018 and 2019 to evaluate the impacts of different irrigation regimes on yield and quality of three russet potato varieties. For Russet Burbank, fry quality at harvest and at 4 and 8 months after harvest was assessed. During early growth stages, the standard practice of irrigating to maintain 60–80% soil moisture was employed. The irrigation treatments were applied during the late tuber bulking and maturation growth stages, and consisted of irrigation at 125%, 100%, 75%, and 50% of daily evapotranspiration (ET). We found that 125%ET provided no increase in total yield and marketable yield compared to other treatments in 2018, and it produced similar marketable yield to 100%ET in 2019. Total yield, but not marketable yield, of 125%ET and 100%ET was significantly higher than the number under 50%ET in 2019. In both years, increasing irrigation rate led to a decrease in irrigation efficiency and water-use efficiency. Irrigation rate had no significant effects on tuber quality at harvest and during storage. This study indicated that over-irrigation at 125%ET was not beneficial to profitable potato production in the Upper Midwest of the US, and deficit irrigation at 75%ET during late tuber bulking and tuber maturation could potentially result in more sustainable water use while not jeopardizing tuber growth. The results support the possibility of adopting late-season deficit irrigation for growing potatoes in the region, though more years of research would allow for a better understanding of the impacts of this practice.

Organic cultivation practices enhanced antioxidant activities and secondary metabolites in giant granadilla (Passiflora quadrangularis L.)

Passiflora quadrangularis L. belongs to the family Passifloraceae which bears larger fruit with edible juicy mesocarp and pulp known as a good source of phytochemicals. Cultivation and plant management practices are known to influence the phytochemical compositions of agricultural produce. This study aimed to examine the influence of the cultivation practices on the antioxidant activities and secondary metabolites of the organically and conventionally grown P. quadrangularis. Findings revealed organically treated P. quadrangularis plants showed enhancement in their antioxidant properties and secondary metabolites profiles. Among the plant parts, leaves of P. quadrangularis grown organically possessed higher antioxidant activities compared to the conventional in all assays evaluated. The antioxidant activities in the edible parts of the P. quadrangularis fruit have also been enhanced through organic cultivation with significantly higher total phenolic content and DPPH in mesocarp, and the pulp showed higher total flavonoid content, DPPH and FRAP. This observation is supported by a higher level of vitamins and secondary metabolites in the samples. The secondary metabolites profile showed mesocarps were phenolic rich, the pulps were flavonoids rich while leaves showed good composition of phenolics, flavonoids and terpenoids with outstanding antioxidant activities. The common secondary metabolites for organically produced P. quadrangularis in different plant parts include 2-isopropyl-3-methoxycinnamic acid (mesocarp and pulp), myricetin isomers (pulp and leaves), and malvidin-3-O-arabinoside isomers (pulp and leaves). This study confirmed that organic cultivated P. quadrangularis possessed higher antioxidant activities contributed by its vitamins and secondary metabolites.

Accumulation rates of natural radionuclides (40K, 210Pb, 226Ra, 238U, and 232Th) in topsoils due to long-term cultivations of water spinach (Ipomoea Aquatica Forssk.) and rice (Oryza Sativa L.) based on model assessments: A case study in Dong Nai province, Vietnam

In topsoils, the activity concentrations of natural radionuclides (hereafter NRs) increase due to the addition of NRs from fertilizers, irrigation water, and air dust pollution. On the other hand, various physical-chemical and environmental processes such as radioactive decay, volatilization, leaching, erosion, and plant uptake were responsible for the decrease of the activity concentrations of NRs in the topsoils. In this study, behaviours of ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³⁸U, and ²³²Th in topsoils were modelled by the CEMC soil model and the HYDRUS-1D model. An exponential equation was proposed for estimating the accumulation rates of these radionuclides in the topsoils. Long-term accumulation of radionuclides was assessed for water spinach (Ipomoea Aquatica Forssk.) soil (hereafter VES) and rice (Oryza sativa L.) soil (hereafter RIS). We found that the current agricultural practices caused the increase of ⁴⁰K activity concentration in the water spinach soil, and ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, and ²³²Th activity concentrations in the rice soil. The accumulation rates of radionuclides were in the order ²³⁸U < ²³²Th < ²²⁶Ra < ²¹⁰Pb < ⁴⁰K. 25 years of cultivation with water spinach can increase/decrease + (165 ± 6) Bq of ⁴⁰K, - (8.2 ± 0.7) Bq of ²¹⁰Pb, - (4.3 ± 0.2) Bq of ²²⁶Ra, - (7 0.3 ± 0.3) Bq of ²³⁸U, and - (1.8 ± 0.1) Bq of ²³²Th in 1 kg soil. For rice cultivation, these values are + (1004 ± 39), + (3.3 ± 0.2), + (3.0 ± 0.2), - (5.1 ± 0.3), (2.2 ± 0.1) Bq kg^-1 for ⁴⁰K, ²¹⁰Pb, ²²⁶Ra, ²³⁸U, and ²³²Th, respectively.

Levels of 226Ra in groundwater samples collected in Phu Yen province, Vietnam associated with health risks to local population and impacts on the maize (Zea mays L.) soil

Groundwater is a major source of drinking water and agricultural water in some regions of the world. However, it contains a high level of 226Ra that is potentially hazardous to human health and the environment. Normally, the activity concentration of 226Ra in groundwater is determined to assess the quality of groundwater that can be used as drinking water. There are few studies on the accumulation of 226Ra in the agricultural soil due to irrigation with groundwater. In this study, levels of 226Ra were determined on over 60 groundwater samples collected from the public water supply wells in Phu Yen province, Vietnam. Besides assessment of the health risks to population due to drinking groundwater samples, the impact of groundwater irrigation to the maize field in the study area was studied. For this purpose, two chemical fate models were applied and the comparison of their results was performed. Based on the model assessments, we predicted that the present agricultural practices increased the 226Ra activity concentration in the maize soil, and the level of 226Ra activity concentration in the topsoil can exceed the recommended level at 11.4 years of the present agricultural practices on the maize soil.

Rootstock x Environment Interactions on Nitrogen-Use Efficiency in Grafted Tomato Plants at Different Phenological Stages

The use of grafting techniques for horticultural crops increases plant tolerance to various abiotic and biotic stresses. Tomato production under greenhouse conditions relies on plants grafted onto vigorous rootstocks because they sustain crops for longer periods. Growers under Mediterranean conditions usually grow crops in passive greenhouses during the summer and winter season, to provide fresh products throughout the year. No information is available with regard to the effect of the environment on nitrogen-use efficiency (NUE) in tomato plants grafted onto rootstocks with different vigor. In the present study, NUE, along with its components—uptake (NUpE) and utilization (NUtE) efficiencies—were evaluated in tomato plants grafted onto two interspecific rootstocks, conferring medium (“King Kong”) or high (“Kaiser”) vigor to the plants. The evaluations were carried out during the vegetative and reproductive stage in plants subjected to different environmental conditions resulting in different plant growth rates. The grafting treatments did not affect NUE, NUpE or NUtE in young plants, but at the reproductive stage, differences were found during the summer season (high N demand) where the vigorous rootstock increased NUpE from 55%, in non-grafted plants, to 94%, with the consequent differences in NUE. During the winter crop, no differences in NUE were found between the vigorous rootstock and non-grafted plants, but the less vigorous (cold-tolerant) rootstock enhanced NUpE. Significant positive relationships were found between plant growth rate and both NUE and NUpE, while NUtE decreased with increasing growth rate.

Ecological and Economic Sustainability in Olive Groves with Different Irrigation Management and Levels of Erosion: A Case Study

In the last 50 years, both the agricultural labour force and irrigated land area have increased almost eightfold in Spain. The main objective of irrigation, in the short term, is to increase agricultural production. However, in the long term, the environmental externalities of irrigation and its direct relationship with soil erosion processes are more uncertain and still poorly studied. In this study, in an olive-growing region of Andalusia, Spain, the variation of several soil parameters related to irrigation and erosion levels was analysed. The results showed that irrigation, while increasing the productive level of the olive groves, entails a progressive alteration of the soil, modifying physical aspects (greater compaction and humidity of the soil together with lower gravel content, porosity and soil weight) and chemical aspects (reduction of the organic matter of the soil and the content of nitrates) that can aggravate the consequences of the erosive processes. In the long term, the productive benefit attributed to irrigation could be unsustainable from an ecological and, consequently, economic point of view. In addition, the lack of sustainability of olive irrigation agroecosystems could be exacerbated by the future restrictive impacts of climate change on water resources in Mediterranean environments. This situation demands spatial planning and alternative management based on soil conservation and rational and efficient forms of irrigation to ensure the sustainability of olive groves and their economic viability.

Regulating nitrate excess in lettuce-planted greenhouse soil with available carbon addition through irrigation

Nitrate excess is common in greenhouse soils, imposing environmental risks and degrading vegetable quality. In this study, the effectiveness of adding sucrose as available carbon through irrigation to cut nitrate excess in lettuce-planted soil was investigated under impacts of soil texture and irrigation type. In the pot experiment using two loam soils of same origin with different clay to sand ratios (50.2% and 39.8%) and nitrate excess (116.1 and 417.7 mg/kg N), three-time sucrose addition through flood irrigation was more effective in lowering net formation of nitrate-based inorganic N and increasing lettuce yield in the soil with the higher clay to sand ratio, and sucrose addition at 150-450 mg/kg reduced nitrate accumulation and leaching, and nitrate content of lettuce at harvest by 62.5-89.6%, 19.3-36.1%, and 11.4-76.0%, respectively. In the micro-plot field experiment with two-time sucrose addition at 0.6-1.2 g/L through furrow irrigation (42 mm) into two other soils of same origin with different clay to sand ratios (56.9%, 48.4%), nitrate accumulation at 0-30-cm depth at the prone-leaching furrow location at harvest decreased by 30.9-36.0% under the higher clay to sand ratio but increased by about 35% under the lower clay to sand ratio. The nitrate content and yield of ridge-planted lettuce was less affected in either soil. Hence, carbon addition rate, irrigation type, and clay to sand ratio all affected the effect of available carbon addition on nitrate accumulation in vegetable-planted soil, and their joint impacts need better quantification for cutting nitrate excess in soil and improving vegetable quality and even yield.