The effects of irrigation on root density profiles of potato, celery, and wheat

Irrigation rate should correspond to the effective root depth, however, crop root growth is influenced by a number of factors, and little data is available on the impact of irrigation. This contribution presents the results of several experiments in which the influence of sprinkler or drip irrigations on root density distribution of shallow, medium and deep rooted crops within the soil profile were studied. Irrigation significantly increased the root density of potato, celery, and wheat in the topsoil zone. On the contrary, at most cases there was only a slightly reduced root density in the subsoil layers. Total root length, to maximum root depth, only increased significantly with drip irrigation in potato. The root depths of these crops were not significantly modified by irrigation. The results suggest that the use of a constant value for the calculation of maximum irrigation depth in a specific crop may not correspond to the variability of root depth nor the distribution in different years or fields

FATIMA Czech pilot

In FATIMA project, a pilot site in Czechia was established to demonstrate how precision agriculture may serve for optimizing crop yields as well as for protection of water quality, since the pilot is located in Czech largest drinking water reservoir catchment. The pilot site Dehtáře is situated in the south-west Bohemo-Moravian Highland. The site contains tile drainage and is of very heterogeneous soil conditions; from shallow, light and stony Haplic Cambisols to heavy Haplic Gleysols, with profoundly different water regimes. For the field trial (spring barley in 2016), crop yield potential was determined from crop statuses as captured by satellite images) eight years back, assessed by Enhanced Vegetation Index. Based on this, as well as on a detailed soil survey and repeated soil sampling, variable fertilizer application zones (70 – 120%) were delineated and mineral fertilizers distributed accordingly with GPS operated spreader three times from late April to late May. The rest of the site was fertilized uniformly. Soil water regime (soil moisture, soil water potential) was monitored continuously on eight spots and real-time broadcasted by wireless sensor network to WEB GIS interface via SensLog solution, adopted from FOODIE project. In the same spots, soil water was sampled by gravitational soil lysimeters. Precise harvest showed a general agreement with the delineated application zones and yield potential, however, some ambiguities were revealed, most probably due to changeable soil water regime, as documented by the sensors, as well as due to variable soil chemical properties (low soil pH). Nevertheless, precisely applied fertilizer doses in the application zones brought about 10% higher crop yields with simultaneous better N crop efficiency. Soil water quality samples confirmed that heterogeneous doses of fertilizer in correctly delineated zones is a promising approach for improvement of groundwater quality especially in shallow soils with low water and nutrient retention abilit

Determination of recharge zones by means of vegetation water stress based on remote sensing and ground measurements

The watershed recharge zones with high soil permeability are critical source zones of non-point agricultural pollution. Their delimitation is the condition of targeted agricultural management in protection zones of water resources. The accelerated water runoff from permeable soils of recharge zones reduces actual evapotranspiration and supports faster formation of vegetation water stress in comparison with other watershed parts. Recharge zones delimitation upon this theory was carried out on a small watershed (partially drained) by a combination of aerial photography in the infrared and optical spectrum of electromagnetic radiation, which provided a basis for modelling of surface energy balance components and crop water stress index (CWSI). The best indicators of vegetation water stress determined by statistical analyzes in order to define recharge zones (arable land with closed stand) were revealed evaporation fraction, CWSI and surface temperature. The results were supported by detailed pedological survey