The effects of cultivation method and timing, previous sward and fertilizer level on subsequent crop yields and nitrate leaching following cultivation of long-term grazed grass and grass-clover swards

Abstract

A 3-year field experiment was conducted in 1996-98 near Penicuik, Scotland, to investigate the fate of N released after cultivation of previously long-term grass and grass-clover swards. The effects of timing of cultivations (autumn and spring), tillage methods (no tillage, ploughing to 200 mm and ploughing to 300 mm) and fertilizer N for spring (0, 40, 80 and 120 kg N/ha) and winter barley (0, 60, 120, 180 kg N/ha) on yield, N uptake and nitrate leaching were measured.In 1996, after spring cultivation, on plots previously in grass, spring barley grain yield and N uptake did not respond to N fertilizer, but on plots previously in grass-clover there was a nearly linear response to N. In 1997, the spring barley responded to N fertilizer at all levels. Yields of 1997 winter barley after grass did not show a response above 60 kg N/ha, but increased with fertilizer N up to at least 120 kg N/ha after grass-clover. In 1998, there were strong effects of N fertilizer and cultivation method on grain yield and N uptake of both spring barley and winter barley. Winter barley grain yield was significantly higher in plots previously in grass than in plots previously in grass-clover in 1998, though not in 1997. Winter barley yields were higher than spring barley at the same fertilizer N level.Throughout the 3 years, the no-tillage plots had consistently lower yields than the ploughed plots, but there was no consistent difference between the ploughed and deep ploughed treatments. There were strong interactive effects between tillage and previous sward in 1997. No-tillage under spring barley generally yielded lower than ploughing due to difficulties in weed control and the frequent anaerobic conditions in the soil.Annual leaching losses were relatively small (6 . 4-19 . 6 kg N/ha). In 1996 -97, more N was leached from the plots left in stubble following spring barley than from those planted with winter barley after either spring barley or grass in 1996, but in 1997-98 more N was leached from plots in winter barley than from those in over-winter stubble. Nitrate leaching was least under no-tillage, though the effect was not significant.

Dynamics of upward and downward N2O and CO2 fluxes in ploughed or no-tilled soils in relation to water-filled pore space, compaction and crop presence

“…The high field N 2 O fluxes in the 3-month period early in the first season represented a cumulated N loss in the same range as that for annual leaching losses at this site of 6.4-19.6 kg ha À1 (Vinten et al, 2002) and represents 7.4 and 1.9% if the N added as fertilizer. The highest N 2 O fluxes that we measured from the no-tilled treatment were in cores where the pore system was blocked by water.…”

“…The site is in a cool, moist climate with an average annual rainfall of 866 mm and an excess winter rainfall of 300 mm. Further details of the site and experimental conduct were given by Vinten et al (2002).…”

Influence of Tillage Practices and Crop Type on Soil CO2 Emissions

“…Vinten et al [42] determined, in one year of research, higher, and in the other year of research, lower soil C-CO 2 emissions at no-tillage compared to conventional tillage. On the other hand, many other authors did not determine any significant differences in soil C-CO 2 emissions between mentioned tillage treatments [43][44][45].…”

“…Similar results were reported by Franzluebbers et al [26], who found that CO2 emissions in some years were higher in no-tillage than in conventional tillage, but in other years, the tillage effect was not observed. Vinten et al [42] determined, in one year of research, higher, and in the other year of research, lower soil C-CO2 emissions at no-tillage compared to conventional tillage. On the other hand, many other authors did not determine any significant differences in soil C-CO2 emissions between mentioned tillage treatments [43][44][45].…”

Nitrogen Risk Assessment Model for Scotland: I. Nitrogen leaching

“…It was assumed that highly responsive arable crops such as winter wheat and potatoes would be grown on soils with greater mineralisation rates, typical of the first Scotland, 199597 year after the ploughing of grass. From experiments on N release to cereals after long term grass, a figure of 70 kg N ha 1 was adopted (Vinten et al, 2002) This simplified representation does not account for differences in N processes as a function of soil type, temperature or the availability of soil N stores and as such will limit the potential of the NIRAMS model for predicting responses to changes in land management.…”