Comparison of crop yields and soil conditions during 30 years under annual tillage or grazed pasture

Abstract

Crop yields and soil properties of grazed grass-clover pasture and arable plots at the Grasslands Research Institute, Hurley, UK. were measured over 30 years . Yields of herbage declined from 9-6 t DM/ha in the first harvest year to 4-6 t in years 5 to 8 but subsequently increased (after liming) to give a mean yield of 8-2 t for 1963-84. Yields of barley in plots receiving a seed-bed application of 45 kg N/ha averaged (1962-80) 31 t/ha and, in plots top dressed with an additional 100 kg N/ha, 41 t/ha but after 1969, response to additional N and yield under both N treatments showed a marked decline.Soil carbon increased during the first 10 years under pasture from 1-2 to 1-8% and soil N from 0-13 to 0-17%. These increases, equivalent to 1 t C and 75 kg N/ha per year, occurred at the same time as the initial decline in herbage yield noted above. During the subsequent 20 years, C and N remained relatively constant and herbage yields increased. Soil C and N decreased under 30 years' arable management to 0-8 % C and 0-1 % N, equivalent to a loss of 290 kg C and 25 kg N/ha per year.Major factors that appear to have influenced herbage yields were (i) soil moisture, (ii) accumulation of N in the soil organic matter during the first 8 years and the subsequent increase in the rate of mineralization, and (iii) the action of the earthworm population in creating a stone-free, fertile layer of top soil. As for barley, it was concluded that yields could not be maintained indefinitely on this soil series, as a result of the loss of soil structure and the development of a compact layer of soil at plough depth.

An assessment of the contribution of net mineralization to N cycling in grass swards using a field incubation method

“…Our values are in the middle to upper end of the range of N-turnover rates reported in the literature e.g. 1-3% (Bremner, 1965), 2.5% (Tyson et al, 1990), 3.6% (Macduff and White, 1985), 2-6% (Hassink et al, 1990), 3-7.5% (Ball and Ryden, 1984), and up to 10% , assessed by various techniques for different soil types.…”

“…In another study, also on Frilsham soil, the N content of the soil under a grazed grass/clover sward reached an equilibrium after approximately 10 years (Tyson et al, 1990), so that the high value which we obtained for net mineralization with GC (415 kg N ha -1) may be a feature of a well-established mixed sward. Certainly, high productivity has been achieved from unfertilized mixed swards grazed by sheep (Parsons et al, 1991) which was attributed to rapid cycling of relatively large quantities of N through the soil/ plant/animal system: mineralization rates comparable to those in our study may have contributed to this rapid cycling.…”

Eco-efficient approaches to land management: a case for increased integration of crop and animal production systems

“…Tyson et al (1990) found that changing land use from more or less continuous cereals to pasture increased soil organic carbon from 1.2 to 1.8% in 10 years, with soil N increasing from 0.13 to 0.17%. The annual increments in soil C and N were 1000 and 75 kg ha K1 , respectively.…”

Method and timing of grassland renovation affects herbage yield, nitrate leaching, and nitrous oxide emission in intensively managed grasslands

“…Stubbles of less than five years contain about 40-80 kg N ha -1 and this amount does not significantly increase with ageing (Davies et al 2001;Whitehead et al 1990). The N content of the soil organic matter of grassland increases approximately linearly in young grasslands (\10 years), ranging from 20 to 130 kg N ha -1 year -1 (Cuttle and Scholefield 1995;Hassink 1994;Tyson et al 1990;Whitehead et al 1990). The accumulation of organic matter levels off during ageing and may continue for more than 30-100 years (Jenkinson 1988).…”