Applying slurry in hot conditions can reduce nutrient use efficiency (NUE) and result in vital nitrogen lost if it is not applied accurately. Vogelsang’s Andy Hayhurst offers some top tips to help get the most out of slurry post-harvest.
1. Follow a two-step process. Unlike a chemical fertiliser, slurry is immediately plant available from when it is incorporated into the soil. Plan to apply some slurry immediately but reserve some for when the crop has been planted to help newly establishing plants establish better
2. Managing stored slurry to provide the best quality material for application is of paramount importance to stubble application. Separation will help with this, as will covering slurry to prevent valuable nutrients being lost in hot weather. A well separated slurry will be easier and cheaper to pump, and it can be applied more accurately using dribble bars or a trailing shoe applicator. The liquid will also be absorbed faster, meaning fewer nutrients are lost in hot weather when slurry is prone to evaporation which causes ammonia losses.
3. Not every field is the same, which is why variable rate application is important and can help provide the optimal volume of slurry for the soil. Using soil and slurry test results and field maps, along with precision applicators and variable rate, will ensure the soil gets what it needs. Variable rate is also useful when applying to newly planted crops because it prevents the soil, and early establishing plants, being swamped in slurry.
4. Applying to stubbles is an opportunity to create biomass in soil that will help reduce the impact of winter leaching during inevitable spells of heavy rain. Using separated slurry provides the option to feed the nitrogen-rich, liquid fraction to soil as a starter, which helps to rapidly increase biomass. The solid fraction, which contains most of the P and K, can be subsequently applied as a top dressing in conditions that are not suitable for applying liquid slurry.
5. Timing is crucial. Avoid applying slurry to baked and cracked soils because it will not be absorbed fully and nitrogen will be lost. Rainy days are also a poor and potentially dangerous time to apply slurry, especially post-harvest when soils are dry because it increases the likelihood of potentially damaging run off. Aim for cool, cloudy days when there has been a little rain. This helps the soil to absorb slurry faster and fewer nutrients will be lost by slurry baking on the surface.
