Markstruktur och markvattentillgång

The main purpose of the project was to analyze the importance of soil structure and soil water supply for crop establishment, crop development and yield levels in sugar beet production. The studies started in 1999 as part of the 4T project (sugar beat research project) which started already in 1997 and ended in 2000. A difference in yield levels between neighboring farms with similar basic conditions (soil, climate) was the main reason to start the "pair study" within the 4T project. In the pair study 14 farms were divided into 7 pairs where one farm in each pair had very high yield levels and was called "plus farm" and the neighboring farm had normal yield levels for the area and was called "average farm". The studies in this project have been a part of the pair study. The soil structure was evaluated with a soil structure index and soil physical measurements. Soil structure index is a method to evaluate the physical status of the soil and the effect of the farming system on soil structure. The index consists of three parts. One part where basic soil physical requirements are checked, a farming system part where yearly measures by the farmer are evaluated and finally a soil structure field test. The soil water supply was evaluated with the help of a simple soil water model, soil water content measurements in the field and soil physical measurements. The studies showed that the yield was higher at the "plus farms" in 1999 and 2000 except for pair 4 where the "average farm" had a higher yield level both years. The calculations in the farming system index showed that the farmer can influence the soil structure with his yearly measures. In most pairs the "plus farm" had a higher farming system index than the "average farm". The "plus farm" in general had a better soil structure according to soil physical measurements such as infiltration capacity. The farm with the higher yield in each pair had very often a soil with a greater amount of easily available water, a crop with a better developed root system that could use a greater part of the soil water magazine both in the topsoil and in the subsoil, a crop that could uti1ize the growth potential better and a faster establishment of the crop when the supply of easily availab1e water was good in the topsoil. A good soil structure with a great amount of easily available soil water made it possible for a fast crop establishment, good root development and a good utilization of soil water which created conditions for a high yield.