Nutrient losses by surface run-off following the application of organic manures to arable land. 1. Nitrogen

Abstract

Research was conducted on nitrogen (N) surface run-off losses following organic manure applications to land, utilising a purpose-built facility on a sloping site in Herefordshire under arable tillage. Different rates and timing of cattle slurry, farmyard manure and inorganic N and phosphorus (P) fertiliser were compared, over a 4-year period (1993-97). P losses from the same studies are reported in a separate paper. The application of cattle slurries to the silty clay loam soil increased the loss of solids and NH4(+)-N in surface water flow compared to control plots receiving inorganic fertiliser only, or no treatment, but had little effect on NO3(-)-N losses by this route. Results were consistent with other observations that rainfall events immediately after manure applications are particularly likely to be associated with nutrient run-off losses. Losses via subsurface flow (30 cm interflow) were consistently much lower than via surface water movement and were generally unaffected by treatment. Increasing slurry application rate and, in particular, slurry solids loading, increased solids and NH4(-)-N losses via surface run-off. The threshold, above which the risk of losses via surface run-off appeared to be greatly increased, was ca. 2.5-3.0 t/ha slurry solids, which approximates to the 50 m3/ha limit suggested for slurry within UK 'good agricultural practice'. Sealing of the soil surface by slurry solids appears to be a possible mechanism by which polluting surface run-off may occur following slurry application on susceptible soils. Total losses of NH4(+)-N and NO3(-)-N during the 4-year monitoring period were insignificant in agronomic terms, but average soluble N concentrations (NH4(+)-N + NO3(-)-N) in run-off, ranging from ca. 2.0 mg/l, up to 14.0 mg/l for the higher rate slurry treatments. Peak concentrations of NH4(+)-N > 30 mg/l, are such as to be of concern in sensitive catchments, in terms of the potential for contribution to accelerated eutrophication and adverse effects on freshwater biota.

Nutrients in soil layers under no-tillage after successive pig slurry applications

“…This was confirmed by Aita et al (2006) under conditions similar to the ones in this study. In addition, transfer by runoff occurred as well as reported by Ceretta et al (2010) and Smith et al (2001a). Furthermore, mineral N may be involved in transfer by ammonia volatilization, mainly from soils under no-tillage, once manure is applied onto crop residues without soil incorporation and the transferred quantities may reach 32 % of the total N applied via manure (Mkhabela et al, 2008).…”

“…This rapid transformation of ammoniacal N to N-NO 3 -significantly increases the concentration of N-NO 3 -in soil (Loria & Sawyer, 2005). However, accumulation of N-NO 3 -in soil occurs in the first days after pig slurry application (Chantigny et al, 2004;Assmann et al, 2007;Adeli et al, 2008) and decreases over time due to its transfer by runoff (Smith et al, 2001a;Ceretta et al, 2010) and, mainly, percolation (Daudén et al, 2004;Basso et al, 2005;Bergström & Kirchmann, 2006), as it forms an outer-sphere complex with low binding energy with surface functional groups of reactive soil particles.…”

Aproveitamento pelo milho do nitrogênio amoniacal de dejetos líquidos de suínos em plantio direto e preparo reduzido do solo

“…Deve-se destacar que, no presente trabalho, decorridas 4 horas da aplicação dos dejetos ao solo, ocorreu uma chuva de 40 mm (Figura 1), o que indica que parte do N aplicado com os dejetos pode ter sido perdida via escoamento superfi cial. Smith et al (2001) destacaram que o potencial de perdas de N por escoamento superfi cial, após a aplicação dos dejetos, foi maximizado quando ocorreram eventos pluviais logo após sua aplicação.…”

Validation of the exposure assessment for veterinary medicinal products

“…These findings suggest that the contribution of these mechanisms can be higher than expected, particularly for chemicals with a high binding potential (McLachlan et al, 2002 andPolyakov andLal, 2004). Smith et al (2001) observed relevant contributions of surface run-off including particles losses for manure applications over 2.5-3.0 t ha −1 slurry solids in UK arable lands. But due to the higher run-off/erosion risk of the Mediterranean region a lower threshold should be considered for this area (Arhonditsis et al, 2002).…”