Give recommendations on fertilizer application
The application of lime or other pH correcting material is usually broadcast well in advance of planting so there is sufficient time for the material to react with the soil solution before the crops are planted.
Timing is of great importance with the application of nitrogen, as there is a potential loss through leaching , denitrification and volatilization. Materials like urea should not be surface applied without incorporation, except by banding of dribbling solutions, which reduces volatilization. Under alkaline conditions and high humidity loss of ammonia can occur within a relatively short time.
Phosphorus and potassium
The immobile nature of these elements, except in sandy soils, has resulted in fall applications of them, although there is the possibility of fixation under certain soil conditions. This, of course, reduces the immediate efficiency of broadcasting.
Broadcast/plowdown applications have several advantages:
- high rates can be applied with out injury to the plant;
- nutrient distribution throughout the root zone encourages deeper rooting, while placement causes root concentration around a band;
- deeper rooting permits more root soil contact providing a larger reservoir of moisture and nutrients;
- broadcasting is an economical way to apply certain nutrients on established pastures and meadows;
- broadcasting can provide total fertility to help the crop take full advantage of favorable conditions throughout the growing season.
Factors that must be considered in assessing potential nutrient loss:
- – soil type;
- – climatic conditions;
- – nutrient mobility;
- – method, source, rate, timing of application;
- – cultural practices such as tillage and irrigation.
ROW AND BAND APPLICATION
Row application concentrates nutrients for rapid growth and insures nutrient availability when the root emerges; this is an efficient method to supply nutrients for plants with limited root systems. However, too much fertilizer too close to the seed can decrease germination and injure root hairs due to the existence of a temporary region of high salt concentration near the seed.
The maximum safe amount of starter fertilizer that can be placed in bands depends on the crop to be grown, distance of the band from the seed, the kind of fertilizer, the row width, type of soil and soil moisture. Generally, greater amounts can be tolerated as distance from the seed increases, soluble salts in the fertilizer are reduced, soil moisture is increased, and the soil is of a medium (silt loam) to heavy (clay) texture.
Concentrated fertilizer solutions are frequently the most economic buy. Application by injection is in many cases the best method, as it places relatively insoluble materials into the root zone and prevents or minimizes volatilization losses of nitrogen.
Another advantage of injection is that it gives minimum surface disturbance, which is advantageous in dry land under decreased tillage conditions.