Influence of ley duration on the yield and quality of the subsequent cereal crop (spring oats) in an organically managed long-term crop rotation experiment

Abstract

The ability to maintain crop yield and quality in systems based on nitrogen (N) fixed by legumes rather than from synthetic N fertilisers is fundamental to the long-term viability of organic farming. This paper reports crop yield and nitrogen uptake parameters for the first spring oat crop after grass/clover ley in organically managed ley/arable rotations to indicate the amount of fertility built-up during the ley period. The trial site, at Tulloch in North East Scotland, underwent two complete cycles of 6-year ley/arable rotations with different lengths of grazed ley (3 or 4 years). Trials were sufficiently replicated so that each course of the rotation was present in every year. The rotation containing 3 years of ley was also compared with a similar rotation at a nearby site (Woodside) with lower rainfall and soil fertility over one and a half rotational cycles. Grain yields were consistently higher at Tulloch (5.1 tha −1 compared with 4.5 tha −1 at Woodside) and were unaffected by the length of ley. However, grain N percentage was higher following the 4-year ley (1.38% compared with 1.30% following the 3-year ley). While yields were maintained between the first and second cycles of all the rotations, grain N percentage declined. Annual grain yields of the organically grown oats at Tulloch were not significantly different from National List/Recommended List yields in NE Scotland for oats receiving 100 kg N ha −1 . Results suggest that these particular rotation designs were suitable for maintaining acceptable grain yields under organic management conditions.

Nitrous oxide emissions from European agriculture – an analysis of variability and drivers of emissions from field experiments

“…Following land use change or within rotational systems, there may be a release of mineral N from the organic N pool due to tillage, providing a substrate for nitrification-and denitrification-driven N 2 O release. In organic farming systems this build-up of organic N within the grassland phase of a rotation is used to provide nutrients (particularly N) for subsequent arable crops (Stockdale et al, 2001;Watson et al, 2011). This can lead to some high emissions in individual years from organic farming systems, particularly where the system exists in mild and wet climates such as that at Scottish organic site at Tulloch (despite no apparent input of N in that year).…”

Management Options for Organic Winter Wheat Production under Climate Change

“…Studies suggesting oat as a good LGS exploiter are confirmed by their results [28]. Especially in the oat/plough test method and in the damp hollows, oats were able to take up high levels of mineralised LGS nitrogen in spring (up to 105 kg N ha −1 ).…”

“…By inserting oats, the N-deployment from organic plant matter (decomposed LGS residuals, straw and oat root residues) is more in sync with winter wheat N up-take the following spring. The advantages of oat as an LGS subsequent crop are its extensive root system and high nutrient up-take [28], while as a winter wheat preceding crop, oat's vegetative growth suppresses weeds. As a recovery crop, oat prevents the spreading of fungal pathogens, such as black root rot (Gaeumannomyces graminis) [29,30].…”

Predicting the effect of rotation design on N, P, K balances on organic farms using the NDICEA model

“…Soils data from each site were collected from project reports, site records and published literature (Haggar and Padel, 1996; Lennartsson, 2000; Welsh et al, 2002; Cormack, 2006; Taylor et al, 2006). The bulked soil samples at each site were taken along a W transect twice each year in the case of Elm Farm (Welsh et al, 2002), Warwick University (Lennartsson, 2000) and ADAS Terrington (Cormack, 2006) (after sowing and harvest) and once per year at the SRUC sites (Watson et al, 2011) and at Ty Gwyn (Haggar and Padel, 1996) (January and April, respectively). Samples were analyzed for available P (Modified Morgan's solution at SRUC sites and Olsen's method at other sites), available K (Modified Morgan's solution at SRUC sites and ammonium nitrate extraction at ADAS and Elm Farm), mineral N (potassium chloride solution) and organic matter (loss on ignition).…”