The effect of compacted soil layers on vertical root distribution and water uptake by wheat

Soil compaction strongly affects water uptake by roots. The aim of the work was to examine soil-plant interactions with focus on the impact of distribution of compacted soil layers on growth and water uptake by wheat roots. The growth-chamber experiment was conducted on wheat growth in soil with compacted soil layers. The system for maintaining constant soil water potential and measurement of daily water uptake from variously compacted soil layers was used. Layered soil compaction differentiated vertical root distribution to higher extent for root length than root mass. The propagation rate of a water extraction front was the highest through layers of moderately compacted soil. The root water uptake rate was on average 67 % higher from moderately than heavily compacted soil layers. Correlations between water uptake and the length of thick roots were increasing with increasing level of soil compaction. The study shows that root amount, water uptake, propagation of water extraction and shoot growth strongly depend on the existence of compacted layers within soil profile. The negative effects of heavily compacted subsoil layer on water uptake were partly compensated by increased uptake from looser top soil layers and significant contribution of thicker roots in water uptake.