Effects of soil compaction, water and organic matter contents on emergence and initial plant growth of cotton and sugar beet
The effects of compaction on the emergence and initial growth of cotton and sugar beet plants were studied in pots in a glasshouse experiment. Apart from compaction, the factors studied were two soil types, two initial soil water contents before compaction and the addition of 1% organic matter in the form of vinasse, an alcohol industry waste. Measurements were made of the time to emergence, the daily growth and the final height of the plants after 30 d and the dry matter of the aerial and root parts. A completely randomised block experiment was made with four replications. The results showed that sugar beet is more sensitive to compaction than cotton. Compaction reduced the amount of root dry matter but the aerial part was less affected. Time to emergence was reduced at moderate compaction (around 150 to 200 kPa) and high initial soil water content (15% for the sandy loam and 23% for the clay loam). Mean daily growth and final height of plants showed a maximum at compaction pressures around 100 to 200 kPa. Increased organic matter caused a smaller increase in the bulk density of the soil by compaction but the effect on plants was not clearly revealed because of the adverse effect of the material on emergence time, most probably owing to the sodium content and to the low pH. (C) 1997 Silsoe Research Institute.