The rain we've experienced over the last year has left many areas very wet and soil more vulnerable to damage. A planned and careful approach to spring operations could minimise soil damage and even start remediation in some cases.
Whatever your situation check tyre pressure and axle weights
Many soils will not have adequately dried out and compaction is accentuated by tyres that are too hard and high axle weight. Every effort must be made to use the lowest appropriate tyre pressures for each field operation and to minimise total axle weights, if necessary by carrying part loads of seed and fertiliser to the field. Only radial tyres should be used, cross ply tyres and particularly the super single tyre, found on heavy goods vehicles with tyre pressures of 70 plus psi, should never be used on arable land.
Soil structure trafficking effects (image courtesy of Philip Wright of Wright Solutions)
Note the increased depth of damage as axle weights increase.
Three land challenges – three approaches
Current soil conditions have been mainly determined by three different sets of circumstances and will require different action in each case:
- Land damaged by late harvest of crops,
especially maize and potatoes
In many places this land is in a mess with standing water, which by now may be just water logged soil. Where there is significant clay content this soil will be very 'plastic' and prone to more damage and being pressed further down the profile if great care is not taken. If these soils can be left to drain, assuming that there are operational land drains, this would be the best course of action. However, sometimes pulling a tine through may help to get the water away but there needs to be recognition that there is a high risk of additional damage if this is attempted too early.
- Land cultivated in preparation for autumn drilling before soils became too wet
This land will be extremely vulnerable to compaction but there will be extreme pressure to get back on the land as soon as possible.
On cultivated land at our Cambridgeshire clay loam soil demonstration site last autumn, just one low ground pressure pass of a sprayer increased the time required for water to infiltrate by 200 times, highlighting the vulnerability of these soils.
It is especially in these circumstances where light axle weights and low pressure tyres are essential.
Land that's not been touched since last harvest
Potentially, these will be the first fields that will be fit to travel, and ploughing may be considered but there is a risk of smearing and sealing at the bottom of the furrow. Whichever cultivation program is considered, the number of passes must be minimised and zero till methods considered where possible.
The impact of increased soil density on crop performance
Soil density is difficult to measure accurately but estimating likely density will help formulate appropriate cultivation plans for different fields. The table below indicates the impact of increased soil density on crop performance.
The impact on potential root development must be borne in mind at all times when a machine enters a field at water capacity.
Field assessments to determine soil conditions before field operations
Every field should be assessed before any field operations and this spring it will be even more important to decide the appropriate course of action. Walking fields and digging holes remains the most appropriate method in the short term.
Firstly, digging holes in the top soil and carrying out a VESS (Visual Evaluation of Soil Structure) score is a good start. Everyone can compare soils and guide charts, such as this one from SRUC can help. The objective is to compare soils across the farm to help plan imminent actions.
Where time allows and there is evidence of compaction at the interface of the top soil and sub soil dig deeper to expose the extent of the damage. Although soils may be too wet to effect remediation this spring, conditions should be noted for next autumn when hopefully loosening can be undertaken.
In addition, soil compaction can be identified by using penetrometers but if one is not available a metal rod with a sharpened end can substitute to indicate depth of compaction.
It's important to consider not just harvest 2020 but harvest 2021 and beyond when making cropping decisions this spring. The aim is to get planned crops planted where you can, and where you can't to ensure you consider the on-going implications of alternative decisions. For example, choosing to plant a crop that is late spring sown and late harvested may well have a knock on impact on your autumn drilling plans especially if it is another wet autumn.
When it comes to drilling, timing will be determined by soil moisture and temperature which should be monitored on a local basis. Drilling barley, in particular, into cold wet seedbeds rarely results in adequate establishment; patience is needed!
There will be some land that is so badly damaged that a spring cash crop can't be planted. In these situations consider cover crops to repair soils over the summer. Kings Soil Structure and Vitality mixes will help repair damaged soil through the summer. Discuss the appropriate mix for your soil conditions with your local Kings advisor or Frontier agronomist.
Spring action check list:
- Check tyre pressures and axle weights
- Walk fields and assess current soil conditions
- Review relevant cropping options including summer cover crops, keeping in mind the impact on the longer term rotation.
- Record areas of compaction for remedial action in the autumn.
Taking this pragmatic approach to what is undoubtedly a challenging situation for many will help make the most of the opportunities in the year ahead.