Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

Abstract

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha(-1) on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha(-1), with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha(-1) in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha(-1) at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs.

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

“…Concentrations for the high treatment were calculated as a function of nitrogen addition since nitrogen is documented as the limiting nutrient for seagrasses in many temperate systems (Zimmerman et al, 1987;Touchette and Burkholder, 2000). Nutrient additions were chosen to be really high, comparable to levels used in agriculture in the Shandong province (Ju et al, 2006). The desired quantity of fertilizer was evenly injected with syringes into the sediment for each circular plot of 1 m diameter (0.78 m 2 ).…”

Seasonal temperatures have more influence than nitrogen fertilizer rates on cucumber yield and nitrogen uptake in a double cropping system

“…Fertilizer N use efficiency in intensively managed greenhouse vegetable systems can be less than 10% using conventional management practices (Zhu et al, 2005), consequently large amounts of unused nitrogen are released to the environment through nitrate leaching, denitrification and NH 3 volatilization (Cabrera et al, 1993;Cabrera and Chiang, 1994;Fox et al, 1996;Gollany et al, 2004;Ramos et al, 2002). For example, nitrate-N concentrations in shallow wells around greenhouses in Huimin, Shandong, ranged from 9 to 274 mg N L À1 , with 99% of surveyed wells exceeding the USEPA limit of 10 mg N L À1 , more than half of the samples (53%) exceeding 50 mg N L À1 , and 26% exceeding 100 mg N L À1 (Ju et al, 2006). Double-cropping systems are typical in greenhouse planting systems without supplementary heating or illumination on the North China Plain.…”

Nitrates and phosphates in cave waters of Kraków-Częstochowa Upland, southern Poland

“…Nitrates are characterised by a high degree of mobility and the ability to infiltrate the phreatic zone as a result of leaching processes (DeSimone and Howes 1998;Chowdary et al 2005). The leaching of nitrates from the vadose zone in cultivated areas demonstrates variation over time and space, conditioned by the quantity and the range of applied fertilisers, irrigation of the area, and types of crops (Sylvester-Bradley et al 2001;Ju et al 2006). Colombo et al (2015) noted a high correlation between land use, terrain relief, availability of nitrates in soil, intensity of agriculture, and nitrate content in waters of the phreatic zone (Harter et al 2002;Jordan and Smith 2005;Dunn et al 2005;Liu et al 2005).…”