The effect of a compacted subsoil layer on the development of the maize root system
M. Heinen, H. Schneider, Kui Shan, G. Bakker, Guido Bakema
Abstract
Soil compaction is regarded as one of the major soil threats. Specifically, the formation of dense soil layers at shallow depth may impede proper root development and influence water, nutrient and oxygen availability for roots. The impact of different levels of soil compaction on shoot and root biomass, root diameter and root length density of a (young) maize plant was determined under controlled conditions in 70 cm high soil columns filled with loamy sand for a growth period of 40 d. The control treatment S0 did not have a compacted soil layer and the dry bulk density was uniform with depth, equal to 1350 kg m −3 , and four treatments of soil compaction at depth 30–40 cm were considered: 1397, 1491, 1544, 1605 kg m −3 (S1-S4). The shoot biomass after 40 d significantly decreased from treatments S0 to S4. The root-to-shoot ratio significantly increased from treatments S0 to S4. The presence of a compacted soil layer resulted in thicker roots than in S0, both within and above the compacted layers. There was a trend of increasing root diameter inside the compacted soil layer for S1-S4. The root length density was significantly lower inside the compacted soil layers compared to that in S0, and also lower than in the layers above and below the compacted soil layer. With increasing density of the compacted soil layer the root length density of thicker roots (diameter > 0.2 mm) increased and the root length density of thin roots (diameter ≤ 0.2 mm) decreased at all depths.