Development of precision fertility management systems
The intention of workpackage 3.3 is to get a better insight into the relationships between fertility inputs, inherent soil characteristics and crop composition, technical and sensory quality.
The need to understand and predict soil mineralisation processes
Organic matter (manure, composts, crop wastes, legume fertility building crops) is the main source for N and/or P inputs into soils in organic and many “low input” production systems. The use of compost is encouraged by EU and national government waste recycling schemes and organic sector body standards, because composting may (a) increase the recycling of communal and domestic waste and thereby reduce costs associated with land fill (b) reduce nitrate leaching losses early in the growing season, (c) reduce nitrate content in organic vegetables (d) induces soil suppressiveness against soil borne diseases and (e) reduce pathogen transfer risks associated with manure (the pasteurisation temperatures reached in controlled aerobic composting processes kills enteric pathogens)
However, a substantial proportion of the total N and P in organic matter inputs become available to crops after the organic matter has been mineralised in the soil. The mineralisation capacity/activity of soils is accordingly thought to be a key factor affecting nutrient supply to crops in organic and “low input” production systems. It is therefore essential to increase our understanding about the relationships between N-mineralisation and soil biological activity. It is necessary also to understand the effect of environmental, soil and crop factors on soil biological activity and nutrient release characteristics, so as to predict and manage nutrient supply from organic matter inputs more precisely.
The need to understand relationships between fertility management and susceptibility to diseases
Plant diseases are a major reason for reductions in crop yield and quality in organic and low input production systems. Fertility management regimes, which provide a restricted but balanced supply of macro- and micronutrients to crops have been shown to improve the resistance of crops to certain diseases (including mycotoxin producing Fusarium spp. in wheat). Studies of natural plant communities suggest that restricted availability of nutrients induces an increased allocation of resources to defence mechanisms. There are also studies that suggest that high supplies of available nutrients lead to decreased accumulation of defence related secondary metabolites. It is therefore important to increase our understanding of the effects of fertility management practices on the susceptibility of crops to foliar diseases.
The need to understand relationships between fertility management and crop quality
Certain differences in plant food composition are often, but not always, observed when products from organic and conventional agriculture are compared. This may have been due to differences in fertility inputs. For example, some studies suggest that compost (made from manure or other organic waste) results in higher dry matter, vitamin and mineral nutrient content in vegetable crops than un-processed manure and/or mineral fertilisers used at similar nitrogen input levels. Balanced N-fertilisation has also been shown to improve other quality parameters, such as reduced storage rots in onion, and the improved sensory quality of organic apples; and recent cultivation experiments showed larger bread volumes from organic wheat fertilised with manure/straw that when fertilised with slurry containing similar contents of N and P.
Studies to be carried out
It is therefore essential to gain a better understanding of the relationships between fertility inputs, inherent soil characteristics (those determined under WP3.1) and crop composition, technical and sensory quality.
Selected arable (wheat), field vegetable (onion) and a greenhouse (tomato) model crops have therefore been chosen to address theses deficiencies in knowledge. We will carry out the following studies (sub-workpackages):
WP 3.3.1 Effect of fertility management practices on yield, protein content and baking quality and Fusarium grain infection/mycotoxin contamination in organic wheat production systems. The study include field trial based study focusing on three main variables (a) improved management strategies of preceding legume crops, (b) pre-planting organic matter and (c) late application of water-soluble N-fertilisers
WP 3.3.2 Effect of fertility management practices on crop yield, quality and incidence of foliar diseases in organic onion production systems. The field trial based study is focusing on evaluating and integrating (a) improved management strategies for preceding legume crops, (b) pre-planting organic matter inputs (c) free-living, nitrogen fixing microbial inocula and/or (d) strategies which increase K and P-use efficiency (e.g. clay and raw phosphate amendments of compost).
WP 3.3.3 Effect of fertility management practices on fruit yield, quality in organic tomato
Glasshouse and field trial based study focusing on evaluating and integrating (a) organic matter inputs, (b) arbuscular mycorrhizal and (c) free-living, nitrogen fixing microbial inocula.
WP 3.3.4 Development nutrient budget-based precision farming system & software
Desk study using data from WPs 2.1, 3.1, 3.3, 3.4 and 3.5 to further develop/improve models and algorithms within an existing fertility management software. Selected existing (e.g N_able, www.qpais.co.uk; Eco-plan, Natural farming systems, Durham, UK) or currently developed (e.g. in the EC-project EUROTATE_N QLRT-2001-01100) precision farming systems will be validated for their ability to predict nitrate losses, nitrogen use efficiency and crop yield and quality using data from field studies under WP2.1, WP3.3, WP3.4 and WP3.5. Algorithm development in this project will focus on incorporating soil specific mineralisation and fertility release characterization data for different organic matter inputs into existing algorithms.
Environmental and sustainability audits and cost/benefit analyses on novel strategies developed under WPs3.3.1 to 3.3.3 will be carried out as part of Horizontal activity 1&2. WP3.3 will also provide important data/deliverables for WP3.5 and SPs 4, 5 & 6 (see the graphic presentation)