Winter cover crops on processing tomato yield, quality, pest pressure, nitrogen availability, and profit margins.

Kimberly D. Belfry,Cheryl Trueman,Richard J. Vyn,Steven A. Loewen,Laura L. Van Eerd,Erin Haramoto

doi:10.1371/journal.pone.0180500

Abstract

Much of cover crop research to date focuses on key indicators of impact without considering the implications over multiple years, in the absence of a systems-based approach. To evaluate the effect of three years of autumn cover crops on subsequent processing tomato (Solanum lycopersicum L.) production in 2010 and 2011, a field split-split-plot factorial design trial with effects of cover crop type, urea ammonium nitrate fertilizer rate (0 or 140 kg N ha-1 preplant broadcast incorporated) and tomato cultivar (early vs. late) was conducted. The main plot factor, cover crop, included a no cover crop control, oat (Avena sativa L.), winter cereal rye (hereafter referred to as rye) (Secale cereale L.), oilseed radish (OSR) (Raphanus sativus L. var. oleiferus Metzg Stokes), and mix of OSR and rye (OSR + rye) treatments. Cover crop biomass of 0.5 to 2.8 and 1.7 to 3.1 Mg ha-1 was attained in early Oct. and the following early May, respectively. In general, OSR increased soil mineral N during cover crop growth and into the succeeding summer tomato growing season, while the remaining cover crops did not differ from the no cover crop control. The lack of a cover crop by N rate interaction in soil and plant N analyses at harvest suggests that growers may not need to modify N fertilizer rates to tomatoes based on cover crop type. Processing tomato fruit quality at harvest (rots, insect or disease damage, Agtron colour, pH, or natural tomato soluble solids (NTSS)) was not affected by cover crop type. In both years, marketable yield in the no cover crop treatment was lower or not statistically different than all planted cover crops. Partial profit margins over both years were 1320 $ ha-1 higher with OSR and $960 higher with oat compared to the no cover crop control. Thus, results from a systems-based approach suggest that the cover crops tested had no observed negative impact on processing tomato production and have the potential to increase marketable yield and profit margins.

Highlights

Processing tomato is among Canada’s most lucrative field-grown vegetable crops, at an estimated annual farm gate value over $70 million CAD [1]
Along with soil moisture and temperature, plant carbon to nitrogen (C/N) ratio is a determinant of residue decomposition that depends on plant growth stage [12]
In autumn 2009, cover crop biomass was greatest for oilseed radish (OSR) treatments (2.8 Mg ha-1)

Summary

Introduction

Processing tomato is among Canada’s most lucrative field-grown vegetable crops, at an estimated annual farm gate value over $70 million CAD [1]. Processing tomato production in Canada takes place largely in two southwestern Ontario counties, Essex and Chatham-Kent. These regions feature rich soils and an extended growing season with sufficient rainfall or access to irrigation that are ideal for high value vegetable production. In this temperate climate, vegetable harvest typically occurs from midAug. to mid-Sept. C/N is generally high for cereal grain crops when compared to legumes [13,14]

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Conclusion