AbstractsSociology

In many parts of the world rice is the stable food, responsible for up to two thirds of the calorie consumption. Many small scale farmers have limited access to inorganic fertilizer. The purpose of this study is to investigate how agroforestry practices affect rice yield and the soil parameters carbon, nitrogen and phosphorous; and under what circumstances is it favorable for small scale rice farmers to adopt agroforestry practices? In the present study we review the theory of rice production and agroforestry. A meta-analysis has been conducted on rice yield and soil properties, C, N and P, in rice-agroforestry as compared to conventional rice farming. 297 studies were reviewed whereof ten studies fulfilled the requirements and were included in the meta-analysis. The yield results showed that when no mineral fertilizer is available rice yield significantly increased by 36% (P=0.05) with the introduction of agroforestry. On the other hand if mineral fertilizer is available the results showed conventional farming yielded 28% more than agroforestry (P=0.0002). Generally we dealt with two groups of agroforestry practices. Systems with trees in the field, and systems with tress away from the field. The results show a clear difference between having trees in the field, as compared to away from the field. The result showed that systems with trees away from the field gave 0.42 t ha-1 more rice than systems with trees in the field. Soil fertility was on all tested parameters (C, N, P) improved significantly by 5% (P=0.03), 7.4% (P=0.04) and 36% (P=0.0004), respectively, subsequent to the introduction of agroforestry. Furthermore the results showed an increasing trend in soil carbon over time when changing to agroforestry. The results are discussed on the basis of critical realism, meaning that we conclude on the underlying structures, which have defined and constrained the empirical data used in the study. The meta-analytical process of this study, showed that research within rice-agroforestry was relatively short sighted and may not have explored the full benefit of agroforestry e.g. increase in soil carbon, long term effect on rice yield or the disadvantages of tree growth within the field. To give a statistically stronger picture, conduction of more field studies is needed. However the results from this investigation clearly show that the use of agroforestry is a way to improve small holder farmers’ rice yield, when applied according to local conditions.