Neveneffecten van niet-chemische onkruidbestrijding in de landbouw : Een literatuurstudie naar de (neven)effecten op drie groepen: bodemleven, insecten en broedsel

Abstract

Mechanical and thermal weed control techniques are important and commonly used methods in organic plant production systems. These methods gain more and more attention from conventional growers due to among others lower availability of (a number of) herbicides. These methods may have potential (negative) effects on organisms which are present in or make use of agricultural land. This can be either directly through mortality and migration of organisms or indirectly through disruption of the habitat or food source. The aim of this literature study was to research what is known about effects of mechanical and thermal weed control on three groups of organisms, namely 1) soil life such as rainworms and fungi, 2) aboveground soil-dwelling insects and 3) breeding birds and nest success. Mechanical and thermal weed control techniques have a limited negative effect on soil life. Negative effects of both mechanical and thermal weed control on aboveground soil dwelling insects depend on the application timing and the amount and type of biomass that is left behind. The degree of disturbance of the insect population is likely to be larger under warmer conditions and presence of a large amount of (weed) biomass because such conditions stimulate insect activity and abundance. Furthermore, the degree of disturbance increases with a more frequent application of mechanical weed control. Mechanical weed control techniques are destructive for breeding birds and nest success. No information on the effects of thermal weed control techniques on breeding birds or nest success was found. It is important to look at combinations of these weed control methods and other farming practices as integral weed management and to quantify the effects of such management on the three groups of organisms. Within the groups, a subdivision into species or subgroups is necessary in order to properly identify the negative effects on the vulnerable species - threatened or rare species - and to introduce targeted protective measurements. Focus should be on which methods need to be applied in what way, when (timing and conditions) and in what frequency. Development of recognition and protection techniques should also gain more attention in order to prevent loss of organisms which make use of agricultural land. Two examples are nest recognition and caps to protect nests which can both be used to retain the bird population.