Kastelutarve

Kastelutarve, in horticultural contexts, refers to the irrigation requirement of soil or plants—the amount and timing of water needed to sustain healthy growth under specific conditions. The concept is used to evaluate how much water plants need, when to apply it, and how often, to keep soil moisture in an optimal range and to minimize water waste. The exact kastelutarve depends on several factors: soil texture and structure (clay soils hold more water than sandy soils); climate (temperature, humidity, rainfall, and evapotranspiration rates); plant species and developmental stage (seedlings may require more frequent watering; potted plants respond to container size); and management practices such as irrigation method and mulching.

Measurement and estimation methods include soil moisture sensors that monitor volumetric water content, tensiometers that measure matric potential, and simple plant indicators like wilting or leaf turgor. Some systems calculate irrigation needs from daily evapotranspiration estimates (ET) and a crop coefficient.

Effective kastelutarve management aims to meet plant needs while conserving water: scheduling based on soil moisture or ET, using efficient irrigation (drip or micro-sprinklers), improving soil water retention, and avoiding excess irrigation that causes drainage and nutrient loss. In practice, the term is common in greenhouse management, landscape irrigation, and field agriculture, and it is part of broader water-use efficiency planning.

Etymology: kastelu means watering and tarve means need in Finnish. See also irrigation, soil moisture, evapotranspiration.