Irrigation Project Overview: The adaptation goal is to identify optimal combinations of irrigation triggers, irrigation saturation, and nitrogen fertilizer levels to increase crop yields and improve nitrogen fertilizer uptake. We are also comparing traditional vacuum-gauge tensiometer probes with electronic tensiometer probes. Tensiometer probes installed at various depths indicate soil moisture. We have constructed moveable rectangular tables holding parallel hoses with drip emitters which conveniently irrigate plots of grass. If, when, and how much irrigation a plot receives depends on its treatment. Irrigation in some plots is triggered when shallow tensiometer probe readings indicate low soil moisture, whereas irrigation in others is delayed until deeper tensiometer probe readings indicate low soil moisture. Some plots are irrigated until shallow tensiometer probes indicate high soil moisture, whereas irrigation in other plots is prolonged until deeper tensiometer probes indicate high soil moisture. Various nitrogen fertilizer levels and controls add to the complexity of the treatments.
July 27, 2015
July 27, 2015 – Irrigation tables are custom-made to fit over the plots. Pressure-compensating drip emitters ensure an even distribution of water over the plot
August 19, 2015
August 19, 2015
August 19, 2015 –
August 19, 2015 – Irrigated and fertilized grasses were visibly more robust and green than control grasses.
August 19, 2015
August 19, 2015
Looking underneath the irrigation pipes.
August 19, 2015 – Controllers allow timed irrigations. The tables have a fixed number of pressure-compensating emitters which emit water at a fixed rate. Thus water volumes applied to plots are easily estimated with irrigation times.
Summer 2015
August 19, 2015 – Irrigation and fertilizer effects are obvious even at a distance.
July 11, 2016 – Irrigation trial plots clearing showing fertilization effects. Irrigation tables have been removed to add tensiometers to the system. Irrigation has not yet started for 2016.
July 11, 2016 – Tensiometers are being set up in the plots. A tensiometer measures soil moisture. It measures the tension or suction that plants’ roots must exert to extracct water from the soil. This tension is a direct measure of the availablity of water to a plant.
