Keywords: Nitrification inhibitors, Urease inhibitors, Controlled release fertilizers, Slow release fertilizers, Nutrient placement, Fertigation

Despite remarkable developments in crop production over the past five decades nutrient use efficiency (NUE), especially that of N, and P remained relatively low. Commonly applied nutrients under conditions of poor management/control over fertilizer and water supply pose serious concerns regarding environmental, health, energy and resource conservation aspects. Poor control of nutrient application makes them prone to economic losses as well while the plants are exposed to non-optimal conditions, which adversely affect potential yields and food quality.

This presentation deals with modified methods of fertilisation, which improve nutrient use efficiency (NUE) and reduce environmental hazards as compared to common fertilisation. The paper presents and discusses modifications/ improvements that can be achieved in the following ways:
i. Changing or modifying fertilizer properties by processing, which can be achieved by:
- addition of bio-amendments/stabilisers such as nitrification inhibitors (NIs) or,
- coating or reducing solubility of fertilizers to form slow or controlled release fertilizers (SRFs or CRFs)
ii. Improving application methods in two main directions:
- by positioning the nutrients in bands, nests or super-granules, or
- by precise delivery of the nutrients via micro-irrigation, which is designated fertigation.

The principles of each of the modifications are described, stressing the specific area where they may fit in and the advantages and disadvantages of each of the proposed methods. Special attention is paid to the possibility of reducing environmental hazards, while maintaining high yields and quality products.

Prof. Avi Shaviv, Faculty of Agricultural Engineering, Technion IIT, Haifa, Israel.

24 pages, 104 refs.