What field to irrigate first? pF curve helps!

18 July 2022

In the scorching heat of these days, growers and farmers all over Europe are struggling with one important question: what field do I water first? And how much water do I give? The pF-curve on the analysis report of Fertilization Manager offers a handy tool for making the right decision. 

Of course, the crop and the growth stage the crop is in, are an important factors that determine whether irrigation is necessary. In addition, the water-storage capacity of the soil is important; in popular terms 'the sponge effect' of a field. One field will retain moisture longer than another, sometimes adjacent, field.

Steep pF-curve

How much water a field can hold and how easily the crop can absorb water can be read from the pF-curve. This curve is part of the analysis package Fertilization Manager from Eurofins Agro. The pF-curve shows how much water the soil can absorb, between the limits of 'wilting point' and 'field capacity'. The steeper the pF-curve the smaller the amount of water the field can hold.  

To quickly decide what field to water first, it is helpful to compare all the pF-curves of the different fields, side by side. The field with the steepest curve needs water first, because this soil contains the smallest amount of water. 

Maximum gift

For the pF-curve on Fertilizer Manager mentions:

Watering more than the recommended amount, is unnecessarily expensive. It costs a lot of water and fuel. Besides, it allows nutrients such as nitrate (NO3), sulphate (SO4), potassium (K) and boron (B) to leach out or nitrogen (N) to volatilize through denitrification. Large watering applications are therefore best divided into several small amounts.