This meant that a controlled amount of water could be applied to the tree. The trees exposed to rainfall would be expected to have greater drainage than from the trees with regulated irrigation. Heavy rain towards the end of summer is especially likely to cause the leaching of mobile chemicals and nutrients beyond the root zone because the soil is more likely to be saturated, and the tree will be transpiring less than in mid-summer. Measuring and modelling leaching of nutrients in the soil Iris Vogeler Understanding how surface-applied fertilisers move through the soil can give us a better understanding of when and why we will get fertiliser loss. Water, and hence solutes, does not flow uniformly through the soil.
Water moves much faster through large pores than small ones.
HortResearch scientists have been studying solute transport by using large columns of soil in the laboratory to represent soil in the field. The researchers use mathematical equations to calculate the movement of solutes through the soil. This suggests that cations applied in fertilisers are more likely to be retained near the soil surface. The ARC was finding that, in general, the current monitored water usage does not justify the volumes of water requested in the resource consent applications. In Auckland, as in other regions around New Zealand, very little information exists on the water use by specific crop types, as well as differences in climate and soil types.