Quantifying the effect of interactions between disease control, nitrogen supply and land use change on the greenhouse gas emissions associated with wheat production

Abstract

A method for calculating the effect of disease control on greenhouse gas (GHG) emissions associated with wheat production, reported previously, was developed further to account for effects of disease control on the amount of fertilizer nitrogen (N) which should be applied and on changes in land use. Data from nine randomized and replicated field experiments from the UK and Denmark showed that the economic optimum N input to winter wheat was greater if diseases were controlled by fungicides, than for untreated wheat. The GHGs associated with this additional N largely negated the benefit to emissions per tonne of grain resulting from disease control. However, the mean grain yield obtained without fungicide treatment was 6AE71 t ha, compared to 8AE88 t ha )1 with fungicide treatment, if N input was optimal for each situation. In the absence of disease control by fungicides, and assuming that the optimum N rate was used, an additional 481 kha of wheat would be required to maintain UK wheat production at the current level. If the additional land area came from converting temperate grassland to arable production, the GHG emissions caused by ploughing grassland would cause emissions to rise from 503 to 713 kg CO 2 e per tonne of grain produced. This would result in an additional 3AE15 Mt CO 2 e per year to produce the typical UK annual production of 15 Mt. This analysis reinforces the importance of winning the 'arms race' against pathogen evolution towards fungicide insensitivity and virulence.

Synergism of Nitrogen Rate and Foliar Fungicides in Soft Red Winter Wheat

“…At Ridgetown and Lucan in 2010, the maximum yields were produced with N rates between 100 to 170 kg N ha -1 with the T123 fungicide treatment; yields declined at the highest rate of N where no fungicides were applied (likely in part due to lodging and harvest losses at these two sites). The difference in response between the UTC and the T3 and T123 fungicide treatments suggests that the most economical rate of N may vary with efficacy of disease control by fungicides, as reported by others (Olesen et al, 2003a;Berry et al, 2010).…”

Assessment of Greenhouse Gas Emissions in Winter Wheat Farms Using Data Envelopment Analysis Approach

“…These differences are the consequences of different cultivation systems. In organic farming, farmers do not apply mineral fertilizers and pesticides, therefore GWP is lower than A -small farms, B -medium farms, C -large farms [17]. The performed analysis shows that GHG emissions per hectare depend on farm size and ranged from 2,378 kg CO 2 eq.…”

“…Khoshnevisan et al [18] reported total emissions of 2,711.58 kg CO 2 eq.·ha -1 for wheat production. In Berry et al [17] studies, GHG emissions were very strongly influenced by the N fertilizer rate and disease control, and ranged from 1,498 to 4,176 kg CO 2 eq.·ha -1 . Therefore, it is very important to define optimum doses of agricultural inputs in order to limit unnecessary outlays and decrease emissions.…”

Nitrous oxide mitigation in UK agriculture

“…Soil moisture in the days prior to fertilizer application can also be important in influencing emissions (Dobbie et al 1999). Berry et al (2010) suggested that the application of N early in the growing season (i.e., February-March) when soil temperatures are generally low may reduce the potential for N 2 O loss. However, this approach would need to be balanced against the greater risk of increased NO À 3 leaching if significant rainfall were to occur following fertilizer application to soils close to field capacity.…”