In the first of a series of Healthy Soils articles supported by the advice of agronomists from Hutchinsons, Martin Rickatson seeks guidance on soil management in established winter crops and in advance of spring drilling.
Travelling in very wet fields and making ruts can risk creating damage lasting for years.
That is the dilemma for combinable growers this spring – whether seeking to treat winter crops or plant spring ones – says Toby Kellie, Gloucestershire-based agronomist for Hutchinsons.
Early identification of any soil structure remedial requirements and avoiding further problem creation will be critical to crops’ success, he believes.
He says: “Dig to identify the depth of any compaction on spring crop land, but don’t cultivate to drain.
Rapid passage of water will take with it fine soil particles, creating a deeper sediment layer that compacts, reducing pore capacity and discouraging aerobic activity which supports biological function, affecting extraction and delivery of nutrients to the plant.
“It’s pointless subsoiling spring crop land now.
Subsoil won’t be dry enough to crack – it will smear, bring up wet soil and create further compaction.
“Neither should topsoil be cultivated too fine prior to drilling.
“Aim for weatherproof surface creation using the natural soil structure to allow water infiltration via capillary action.
“Keep green cover as long as possible to maintain structure, but spray off heavy cover crops – especially those with high cereal content – a month ahead to reduce allelopathy risks.
“Shallow cultivation, leaving residue exposed, will help protect soil and support machinery.
“Rolling post-drilling should generally be unnecessary, helping tillering only where seed-soil contact is poor on light, puffy land.
Don’t drill too early as black-grass may not chit until late March.
Spring barley works well here, happily drilling late with little yield penalty.” Turning to established winter crops, early nutrition will be essential given many are backwards and shallow-rooted, and nutrients may have been washed from the root zone, says Mr Kellie.
“Even if reducing total application to poorer-potential crops, little-and-often applications will reduce the risk of antagonistically affecting backward crops.”
Soil and tissue testing are key to detecting deficiencies while still rectifiable, he emphasises.
“Once seen, damage is done.
These conditions heighten deficiency risk and shallow roots reduce nutrient access.
“Correlate nutrient requirements with soil/tissue and fresh weight/ dry matter testing results, and check each product’s element delivery, particularly with nutrients supplied in formulations.
“Sulphates and nitrates are most valuable, while carbonates are too heavy and don’t translo- cate quickly.
Beware of tank mixes and scorching from application timing, mixtures or the product’s salt index.
Maintaining green leaf will be crucial to mitigate yield loss from poor establishment.
“Consider growth promoters and rooting products to help plants access water at depth should the topsoil dry out later.
Phosphite and zinc can be particularly beneficial.
Biostimulants are worth considering, but take advice and select carefully.”
For those with fields which were intended for winter crops but did not get drilled, and for which there are no spring crop options whatever the reason, the benefits of fallowing should be considered, believes Cambridgeshire-based Hutchinsons agronomist George Baxter.
“It offers a good winter wheat or oilseed rape entry this autumn, but needs managing properly.
Fallowed ground may benefit from cover crop establishment to protect, repair and restructure soil and feed its flora and fauna.
“Agronomists can advise on mixture creation to meet specific farm and field circumstances.
“As with other crops, if soil repair appears necessary ahead of cover crop establishment, dig to inspect the profile before deciding the appropriate response.
With friable dry soil deeper in the profile, overworking these soils will overdry them if there’s a prolonged dry spring period.” A fertility cover crop will feed soil biology on fallowed land, agrees Toby Kellie.
“It will absorb sunshine, rainfall and nutrients and store them for the next crop, helping improve nutrient utilisation efficiency, especially given likely rain-induced losses.
“It will also prime the structure for that next crop, with roots and the air spaces they create helping build its resilience and keeping soil biology functioning, while extracting water from depth to provide the next crop with moisture.
Above-ground growth protects the soil surface and, once dead, the decaying matter provides nutrients and protection.”
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