Effect of subsurface drip fertigation on plant growth and yield

Since over recent decades, the input of reactive N in agricultural soils has increased by 800 %. These high nutrient application levels needed to reach a high productivity have negative consequences on the environment. As the storage capacity of the agricultural soil and the uptake capacity of the crops are exceeded, a great part of nutrients may get lost through leaching from the soil to the deeper ground water or through gaseous fluxes (N₂ and N₂0) to the atmosphere. Until now, the attempts of agricultural research for a better control of nitrogen fluxes have not reduced losses to acceptable levels. Therefore, nutrient strategy management has to fundamentally evolve to reduce significantly nutrient losses. Applying nitrogen through drip irrigation systems placed below the plough horizon in agricultural fields may be an efficient way of delivering water and fertilizers directly to the plant root in a well-controllable way (Figure below). In such sub-surface drip fertigation (SDF) systems small frequent fertigation applications may avoid water and nutrient losses out of the root zone and increase nutrient uptake of the plant roots. A major concern with SDF is the evaluation of the uniformity. Under SDF, plants are exposed to spatially and temporally variable water and nutrient gradients which affect root architecture and root activity. However, little is still known about the plant response to such heterogeneous water contents and nutrient concentrations as it leads to complex 3-dimensional flow field structures. To provide a better understanding of functional relationships between crop growth and water and nutrient supply under SDF, a modeling approach using crop and root parameters as influenced by water contents and nutrient concentrations is developed.