Abstract
Understanding nitrogen use efficiency (NUE) of crops plays an important role in achieving sustainable production. Intensive agriculture has adversely affected social and environmental issues worldwide over the past few decades. Anaerobic digested residues from the distillery industry (DADRs) can be used in agriculture, thereby recycling valuable organic materials that can supply organic N. An experiment using DADRs in horticulture was conducted to evaluate the performance of different treatments on yield and NUE. The experiment was conducted for five years, growing lettuce, cauliflower, chicory, potato, Swiss chard, catalogna chicory, tomato, pepper, and melon in two different succession schemes. Five fertilization treatments were designed, including a mineral fertilization control, in which nitrogen (N) was supplied according to standard recommendations in the area. The other treatments were an unfertilized control and three treatments in which 50%, 75%, and 100% of the N were supplied by DADRs and the remaining with common chemical fertilizer. Major findings were: (1) Spring–summer crops showed the lowest N-uptake and N recovery, during this period high chemical fertilization can cause environmental problems such as N leaching, and fertilization with 100% DADRs is a viable alternative; (2) fall–winter crops can be fertilized by combining 50% mineral N and 50% organic N, supplying the nutrients required by the crops during the growing cycle.
Highlights
Soil fertility management is a crucial practice for vegetable growers facing the reduction of soil organic matter (SOM) as an obvious consequence of intensive horticultural cropping systems [1,2]and the abundant use of mineral fertilizers
49.94% of total organic matter contents (TOM) and 28.97% of total organic carbon contents (TOC). This material presented a high nutrients content (N, P and K), supporting the idea of a highly nutritive by-product. It showed a low C:N ratio (8.32) and the heavy metal content (Cr, Pb, Cd, and Zn) was below the limits specified by the European Union for digestates used as soil enhancers (The Commission of the European Communities, 2006)
Research made in mid- and long-term periods with other organic materials characterized by high electrical conductivity, such as spent mushroom compost [39,40] or cattle manure [41], did not show difficulties if the product was applied at correct levels
Summary
Soil fertility management is a crucial practice for vegetable growers facing the reduction of soil organic matter (SOM) as an obvious consequence of intensive horticultural cropping systems [1,2]and the abundant use of mineral fertilizers. To counteract the progressive loss of SOM, a regular incorporation of crop residues and/or organic fertilizers from animal farming such as farm manures and slurries (cattle and pig) can be adopted, which are effective in improving soil nutritional status [3]. Another possible practice includes the integration of composts from urban food residues, from agro-industry, or from food processing by-products [4]. Possible amendments usable as potential soil fertilizers are the Agronomy 2019, 9, 463; doi:10.3390/agronomy9080463 www.mdpi.com/journal/agronomy
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