Reducing Nitrate Leaching to Groundwater in an Intensive Dairy Farming System

Abstract

Dairy farming is one of the main contributors to nitrate leaching to groundwater, particularly on soils that are susceptible to leaching, such as light well-drained sandy soils. In the Netherlands, as in many other European countries, these soils are predominantly used for dairy farming. A prototype dairy farming system that has been implemented in practice in 1989 has continuously been adapted since then to meet environmental standards (i.e. the EU-standard of 50 mg NO 3 À l À1 ) without reducing milk production intensity (11900 kg ha À1 ). After an initial decline in nitrate concentration from 193 mg l À1 to 63 upon implementation, it subsequently 'stabilized' at a level higher than the environmental standard: 55 mg l À1 . The goal of this paper is to examine causes of excessive nitrate leaching. This was done by relating measured nitrate concentrations with management characteristics such as N balances, cropping patterns and grazing intensities. Special attention was paid to aspects that were supposed to be conducive for leaching: crop rotation of grass and maize and grazing. No evidence was found for enhanced nitrate leaching due to the rotation of grass with maize compared to permanent cultivation. This could be ascribed to the reduction in fertilization levels in first and second year maize with 90 and 45 kg N ha À1 , respectively to account for the expected N release from the ploughed-in grass sod. Triticale was found to lead to higher leaching than grass or maize which is attributed to its poor growth in the period that it should function as catch crop in maize. Grazing contributed to a nitrate increase of about 30 mg NO 3 À l À1 on grassland. As grazing management and intensity is already strictly optimized in order to restrict nitrate leaching, this result underpins the need to develop sustainable grazing methods on soil that is susceptible to nitrate leaching.

Soil Carbon and Nitrogen Stocks of Different Hawaiian Sugarcane Cultivars

“…However, less information in regard to N leaching is available for tropical and sub-tropical, undeveloped agricultural regions. Nitrate produced through nitrification processes in the upper layers can subsequently move downward and accumulate in deeper layers [64,65]. However, in our study, no statistical difference was found for dissolved nitrogen in the form of nitrates (NO3-N) in the whole soil profile (0-120 cm) (Data not shown).…”

Use of long-term monitoring data to derive a relationship between nitrogen surplus and nitrate leaching for grassland and arable land on well-drained sandy soils in the Netherlands

“…Evidence for a decrease in grazing are the increased mowing percentage by a factor 1.7 (LMM data not shown) and the decreased ammonia emission during grazing, from 13.1 million kg in 1990 to 0.8 million kg in 2012 (CBS 2014). Lower nitrate concentrations in grass cutting systems than in grass grazing systems were reported by others (Nevens & Rehuel 2003;Verloop et al 2006). Hansen et al (2012) showed that urinations of ruminants on grazed pastures increased the risk of nitrate leaching.…”

“…The upper metre of groundwater in this region, sampled in the period April-October represents water leached from the root zone reflecting mainly the agricultural practices of the previous agricultural year (Boumans et al 2001). However, Verloop et al (2006) showed that the nitrate concentration in the upper groundwater was also influenced by Year specific long-term median precipitation surplus based on fractions of crop types, soil types and GRCs (overlays with maps) and crop type, soil type and GRC specific long-term median precipitation surplus (Van Bakel et al 2008). agricultural practices of earlier years for a forage maize-grass rotation at an experimental farm with groundwater level between 1 and 3 m below soil surface level (m-SSL).…”

“…Verloop et al (2006) showed that effects of forage maize-grass rotation on nitrate concentrations in upper groundwater on a sandy soil lasted for three to four years. Peu et al (2007), who performed a macro-lysimeter study with a silt loam on which ryegrass was grown in Western Brittany in France, reported that nearly 92% of the nitrate leaching occurred within the first three years after cessation of pig slurry application.…”

Nitrogen Leaching in Intensive Cropping Systems in Tam Duong District, Red River Delta of Vietnam

“…One of the loss pathways in the nitrogen cycle is nitrate leaching from the soil. The magnitude of leaching also strongly varies, depending on such factors as soil type, cropping system, weather conditions, and fertilizer regime (Di and Cameron 2002;Hauggaard-Nielsen et al 2003;Verloop et al 2006). High leaching losses from intensive agriculture may cause high nitrate concentrations in groundwater, which potentially carries health risks.…”