Vegetable cultivation under greenhouse conditions leads to rapid accumulation of nutrients, acidification and salinity of soils and groundwater contamination in South-Eastern China

Abstract

Vegetable cultivation during winter season is economically profitable, but the impact of the intensive production on soil and water quality remains to be studied. The objectives of this study were to investigate the seasonal dynamics of soil nutrients, acidification and salt accumulation in vegetable fields in South-Eastern China. Various vegetables were grown either under open-field conditions or under two different alternating open-field and greenhouse conditions with three replications. Soil samples were collected periodically and analyzed for pH, plant available nitrogen (N), phosphorous (P), potassium (K), electrical conductivity (EC), and urease activity. Water samples from wells located in or near the plots were collected and analyzed for nitrate. Soil nitrate, available phosphate and salt concentrations declined in summer under open-field conditions and significantly increased from December to May under greenhouse conditions. Exchangeable K also decreased in summer season, but did not increase in the spring. Under alternating open-field and greenhouse conditions, nutrient accumulation, soil salinity and acidification were significantly higher for soil used for vegetable cultivation for 2 years (2-y-plot) than that for only half year (0.5-y-plot). The accumulation of nitrate significantly correlated with soil EC and soil acidification. Thirty-two percent of groundwater samples from the 2-y-plot showed a nitrate concentration higher than 50 mg NO 3 l -1 . Conversely, no groundwater sample of 0.5-y-plot showed such high nitrate concentration. It can be concluded that the nitrate accumulation in soil used for vegetable cultivation under alternating openfield and greenhouse conditions not only causes soil salinization and soil acidification but also presents a high pollution potential for groundwater.

Fallow Cover Crop Species and Nitrogen Rate of Fertigated Solution on Cucumber Yield and Soil Sustainability in Greenhouse Condition

“…Meanwhile, N concentration of fertigated solution showed no significant effect on the growth and yield of cucumber (Table 4). These results were same as previous reports mentioning that high N input by excessive application for greenhouse vegetable production could be effectively reduced without yield loss (Olfs et al, 2005;He et al, 2007), and this may not only increase the economic benefit for farmers but also greatly reduce the pollution potential and provide a sustainable use of soil and water resources (Shi et al, 2009). Other study said that the average threshold EC values for total and marketable fruit yield were, respectively, 3.2 and 3.3 dS m -1 , and the total and marketable yield decreased linearly with increasing salinity above a threshold Table 5.…”

“…Soil nitrate, available phosphate and salt concentrations declined in summer under open-field conditions and significantly increased from December to May under greenhouse conditions and the accumulation of nitrate significantly correlated with soil EC and soil acidification. (Shi et al, 2009). Also, as the number of recropping years increased, the soil available N, available phosphorus, available potassium, and organic content increased (Liang et al, 2012).…”

“…In this way, greenhouse soil degradation resulting from recropping of vegetables has become a serious problem for cucumber production (Liang et al, 2012). Thus, if not properly managed, the soil chemical properties would be worsen, and it might lead to a substantial decrease in cucumber yield after all (Shi et al, 2009). Still, in many cases, soil management practices are only focused on maintaining the crop yield, regardless of sustainability determined by soil chemical properties, although there have been some efforts to effectively reduce the accumulated nutrients in the soil surface, such as by using various organic amendments as an alternative to conventional synthetic fertilizer or by cultivating catch crops as a fallow crop in recent times.…”

Effects of Liquid Organic Fertilizers on Plant Growth and Rhizosphere Soil Characteristics of Chrysanthemum

“…The EC of air-dried soil was determined by means of an EC meter (Bante, Ltd., Shanghai, China) with a soil: water ratio of 1:5 (w/v). The soil pH was measured using the pH meter (Agilent technologies, Ltd., Palo Alto, CA, USA) with a soil: water ratio of 1:2.5 (w/v) [41].…”

Preliminary results of spatial distribution of uranium and thorium in soil profiles near a uranium industrial site, Guangdong province, China

“…[8] was adopted. Air dried soil samples were mixed with ultra-pure water with a ratio of 1:2.5 (soil:water) and the pH of the clear supernatant was measured using a pH meter (Sartorius pH-2C, Germany).…”