Across Central Asia, agriculture largely depends on irrigation due to arid and semi-arid climatic conditions. Water is abstracted from rivers and diverted into myriads of irrigation channels. In the past 50 years the area of irrigated cropland has been steadily enlarged with the dried up Aral Sea as a result.

The rivers of the region are largely fed by glacier melt. In the course of climate change, glaciers melt down so that a substantially reduced glacier volume and reduced water runoffs are expected being available for irrigation after 2050. Therefore, it is imperative to adapt the irrigated agriculture and among others increase water productivity and strengthen its resilience against climate change.

Tree wind breaks are one option to reduce water consumption in irrigated agriculture and build resilience against climate change. Tree wind breaks are not new to the region, but have been planted along field borders and irrigation ditches since ever, mainly as a wood source. During Soviet Union times, tree wind breaks were massively propagated. After the independence of the Central Asian countries, energy supply broke down, in particular to rural communities, so that most of those tree wind breaks were cut down to gain fuel wood.

There is a bulk of scientific literature which lists positive effects of tree wind breaks on crop yields, soil moisture, and micro climate. But, the tree wind breaks themselves, as their water consumption, as well as the agrar economy around tree wind break crop systems have not been covered well. Therefore, this project aimed at i) assessing tree and crop water consumption under different tree wind break types and crops and ii) investigating costs and benefits, and eventually income, from those different tree wind break systems. These results have been disseminated and are going to be disseminated through workshops, flyers, university teaching, and video material. This project cooperated closely with the project eAGROFORST (https://www.hnee.de/de/Fachbereiche/Wald-und-Umwelt/Forschung/Aktuelle-Projekte/eAGROFORST/eAGROFORST-E9439.htm), in particular in the field of farm interviews to assess benefits and perception of agroforestry by farmers as well as dissemination.

Project sites were located in northern Kyrgyzstan, south Kazakhstan, and Ferghana Valley. Tree wind breaks of just a single row of poplars, multiple rows of poplars, and multiple rows of elm were investigated in combination with the major crops of the region, cotton, wheat, corn, rice, potato, and barley. Thereby, different wind break spacings from 50 m to 1000 m were investigated.

Elm wind break systems resulted in highest reductions of water consumption (up to -45%), followed by single row poplars (-15%), when compared with the respective crops without tree wind break. This reduction of water consumption in tree wind break systems was found across all crops. Spacing of 50 m and 100 m was the most effective with regard to overall water consumption, i.e. crop and tree water consumption together. Single row poplar tree wind break systems resulted in higher income (+8%) compared to the respective crop without tree wind break, except for rice. The narrow spacing of 50 m resulted in highest income. Multiple row poplar wind breaks did not result in higher incomes. Elm tree wind break systems resulted in highest income improvements when comparing with the respective crop without tree wind break. Yet, elm grows much slower (25 years rotation) than poplar so that poplars (15 years rotation) are more attractive for farmers. Water productivity, here simply expressed as income per unit of consumed water, was highest for single row poplar wind breaks with rice, followed by cotton.