Agroforestry in the Netherlands

Abstract

Agriculture is a major driver of exceeding the planetary boundaries. Therefore, it is a principal sector that requires sustainable change. Agroforestry, described as the deliberate planting of trees on farm land or integrating farmers into forests, is one of the proposed solutions and has gained a lot of (renewed) attention in the Netherlands and elsewhere. A food forest, one of the subcategories, is defined as a human designed system with a variety of edible species grown in vertical layers based on the example of a natural forest. The aim of this research was to provide a more solid basis for the quantification of yields for temperate food forests together with describing advantages regarding nutrients (N, P) and water. To this end, a focal study plot of food forest Schijndel was analysed in which future yields and nutritional carrying capacities (NCCs) were modelled for 2020-2049 with an extrapolation to 2067. Results were compared with conventional fruit-, carbohydrate cropping-, nutand meat systems. The results for this focal study plot showed a slow but steady yield increase towards a fresh weight yield of 7.1 t/ha in 2049 together with a balanced nutritional supply in terms of NCC for kcal (11.0 persons/ha), carbohydrates (13.1 persons/ha), proteins (11.6 persons/ha), fats (13.1 persons/ha) and fibres (23.0 persons/ha) in 2049. Nutritional results were in general significantly higher than few previous studies. The comparison between cultivation systems showed that the food forest plot had the highest overall NCC. Furthermore, the study plot scored high in the category of fats, modest for proteins and was not competitive with the best performing systems among carbohydrates, fibres and kcal. It is hypothesized that a food forest scores high in micronutrient provision as well, although this could not be substantiated in this study. Additionally, several environmental advantages such as reduced nutrient leaching, self-sufficiency and improved on-farm water cycling were indicated. Although, effects such as high annual nutrient removal and high N deposition on those parameters are yet insufficiently understood. In conclusion, a food forest is a more balanced system which takes more time to develop itself than most conventional systems, but offers continuous and (probably) durable yields. The main limitations in this research were the fact that applicable yield data was not readily available together with a premature literature body on effects such as shading on yields. Further research should be redirected towards measuring actual yields, nutrient- and water characteristics and compare those to systems with comparable soil and climate conditions such as adjacent fields together with a further economic assessment for which this study can provide a basis