When the Medicine Feeds the Problem; Do Nitrogen Fertilisers and Pesticides Enhance the Nutritional Quality of Crops for Their Pests and Pathogens?

Abstract

The challenge of maximising agricultural productivity encourages growers to apply high volumes of nitrogen (N) fertilisers and pesticides in order to promote and protect yields. Despite these inputs, pests and pathogens (P&Ps) continue to cause economic losses and challenge food security at local, national, and global scales. P&Ps are a particular problem in industrial agricultural environments, where large-scale monocultures facilitate rapid growth of crop-adapted P&P populations. P&P population growth is strongly dependent upon acquisition of N-resources (e.g., amino acids) from crop tissues, and concentrations of these compounds depend on the metabolic state of the crop which, in turn, is influenced by its growth stage, by environmental conditions, and by agrochemical inputs. In this study we demonstrate that routine applications of pesticides and/or N-fertilisers may inadvertently reinforce the problem of P&P damage in agriculture by enhancing the nutritional quality of crops for these organisms. N-fertilisation has diverse influences on crops' susceptibility to P&P damage; N-fertilisers enhance the nutritional quality and “attractiveness” of crops for P&Ps, and they can also alter crops' expression of the defensive traits (both morphological and chemical) that serve to protect them against these organisms. Exposure of crops to pesticides (including commonly used insecticide, fungicide, and herbicide products) can result in significant metabolic disruption and, consequently, in accumulation of nutritionally valuable amino acids within crop tissues. Importantly, these metabolic changes may not cause visible signs of stress or toxicity in the crop, and may represent an “invisible” mechanism underlying persistent P&P pressure in the field. Given the intensity of their use worldwide, their far-reaching and destructive consequences for wildlife and overall ecosystem health, and the continued prevalence of P&P-associated crop damage in agriculture, we recommend that the impacts of these cornerstone agricultural inputs on the nutritional relationship between crops and their P&Ps are closely examined in order to inform appropriate management for a more secure and sustainable food system.

Potential of microalgae and cyanobacteria to improve soil health and agricultural productivity: a critical view

“…148 However, intensive agriculture with pesticides to control pathogens and pests has caused environmental disturbance and non-targeted effects, with long-lasting and far-reaching consequences. 149 The theory of ‘trophobiosis’, which was proposed by Chaboussou, 150 suggests that the increased availability of soluble nutrients in plant tissues and modification of morphological and chemical defensive traits due to intensive use of chemical fertilizers and pesticides can promote the damage by pathogens and pests in crops. Thus, the vicious cycle of chemical input applications, either repeated or with new compounds, becomes undesirable in agricultural ecologies.…”

Customized nutrient management of onion (Alium cepa) agroecosystems

“…The N fertilization of onions should be managed carefully to avoid reducing bulb loss under storage following the rainiest years 40 . The N requirement should also consider soil quality and disease incidence 28 .…”

“…The centered log ratio (𝑐𝑙𝑟) transformation of compositional data analysis (CoDa) can adjust any nutrient level to the levels of others and account for all pairwise ratios in a composition. The clr values thus bear physiological significance 28 and reflect crop yield and quality [29][30][31][32][33][34] .…”

Early Nutrient Diagnosis of Kentucky Bluegrass Combining Machine Learning and Compositional Methods

“…Nitrogen increases turfgrass foliage color and shoot density non-linearly, but decreases turfgrass belowground biomass linearly [1]. The excessive nitrogen (N) fertilization may inhibit the growth of rhizomes, stolons, and roots [3] [4] [5] [6] and increase the risk of pest damage [7]. Because turfgrass color is easier to monitor than the labour-intensive measure of belowground biomass or shoot density, Badra et al [8] elaborated an easy-to-use rating for foliage color or greenness in the narrow range of 7.0 to 8.9 based on the color chart of the Royal Horticultural Society (London).…”