Articles
LEACHING OF NUTRIENTS AND YIELD OF TOMATO IN PEAT AND ROCKWOOL WITH OPEN AND CLOSED SYSTEM
Also in the closed method rockwool was drip irrigated but the drained solution was recirculated.
The drip irrigation was controlled manually.
The closed peat was a subirrigation system in which the nutrient solution was capillarily soaked into peat slab through a fibrous cloth.
The yield, water consumption, amount of run-off, and its nutrient contents were measured.
The amount of input solution varied to a great degree between the different treatments.
It was lowest in peat and highest in rockwool with a recirculating system.
In the first year the use of water was clearly higher (324 – 665 l/plant) than in the following two years (229 – 506 1/plant).
The water consumption of plants in different treatments did not vary as much as the supplied input solution.
In the open peat system, the amount of run-off was about 10 % and correspondingly in rockwool 19 – 33 % of the input solution.
In the rockwool with the recirculating system there was even 50 % run-off.
The amount of leached nitrate-nitrogen and phosphorus was in the open peat system below 20 % and in the open rockwool system about 40 %.
Yields were higher in the open systems (peat: 27.2 – 31.2 kg/m2/year, rockwool: 26.6 – 32.0 kg/m2/year) than in the closed systems (peat: 21.2 – 26.9 kg/m2/year; rockwool: 25.5 – 28.0 kg/m2/year); perhaps due to over-watering in the closed systems.