Plants absorb nitrates in water through their roots. Nitrates are present in high levels in plant fertilisers. Without nitrates, the amount of chlorophyll in leaves reduces. This reduces the plant's ability to photosynthesise and grow properly, which reduces the farmers' crop yield .
If you make a punnet square out of this, there is no possibility to have a recessive trait because neither parents have it plus dominant is always going to overrule recessive traits.
