Run-off solutions discussed at maize conference

Reducing surface run-off and maize analysis were topics up for discussion at the recent Maize Growers’ Association Conference, Cirencester, Aly Balsom reports.



The UK needs a consistent testing regime for predicting maize silage degradability and metabolisable energy (ME), according to Jonathan Blake, Forage Analytical Assurance Group (FAA).


“As yet, there is no agreed UK equation for energy predication or degradability – this means the same maize silage sample will produce different figures depending on which lab is used.”


In fact, a ring test analysing 20 of the same samples at four different labs showed marked variation in ME predictions, with one lab consistently testing all samples at more than 12 MJ/kg DM.


“This stresses the need to choose labs carefully. It is shameful to admit we do not have a system in place to measure maize effectively,” he said.


“As an industry, we want to feed cows accurately. Maize is a major feed to ruminants, offering a low protein, high starch crop.”


As a result, the FAA and partners are undertaking a project to generate accurate and repeatable equations to predict digestibility and thus ME alongside dry matter, starch and N degradability.


“At the moment, testing for degradability is expensive. This study will generate revealing and practical results and give us a cheaper and faster way of estimating degradability.”


However, to be successful, the study needs 90 samples, each of 110kg DM. “We need samples from commercial maize growers from as wide a geographical area as possible.” Collection begins now and will continue over the next two years.


Run-off 


Sub-soiling maize ground after harvesting is a must to prevent surface run-off, said Richard Smith, the Environment Agency.


“We want to see maize stubble as a thing of the past – when soils are left post harvesting, soil compaction will prevent root penetration, reduce yields and encourage water run-off.”


IGER research demonstrated compacted ground had significantly more water run-off, with maize stubble plots producing 228 litres of run-off compared with just one litre from ground that had been chisel ploughed.


Soil surveys carried out in the south west during winter showed about 38% of sites examined had poor soil structure with signs of surface runoff. “Problems were more significant on lighter soils with about 15% of sandy soils experiencing severe compaction.” Chalkland soils had fewer issues.


Maize land had particularly poor soils with 70% of land showing problems with soil structure post harvesting. However, good soil husbandry can reduce soil problems, said Mr Smith.


“Growers should also aim to prevent damage to soil structure by cultivating land on the day of harvest. And when conditions are wet, ground should be ploughed as soon as possible.”


Choosing early maturing varieties that will give the best chance of an early harvest and drilling early as soon as conditions are right, will also help reduce problems.


And by farmers working in partnership with the Environment Agency, run-off can be reduced significantly, said Mr Smith. And this has been demonstrated at Ottery St Mary, Devon where flooding has been a serious issue for a number of years.


“Following two awful summers where crops have been harvested in the wet and establishment has been difficult, soil compaction and surface run off has been a problem.


“Nearly 100% of ground has got some problem with run-off and although maize is not the cause of the problem, it is a contributor.”


As a result, the Environment Agency purchased a sub-soiler and loaned it out to a contractor to use on local farms free of charge. “On some high-risk soils, mustards were also sown to hold the soil open and stop the battering effect of the rain.” As a result, surface run-off has been reduced.


However, Mr Smith can see no environmental problem with surface run-off from planting grain maize.


“Grain maize gives a wider window in which to harvest, allowing more flexibility in harvest times and the potential to avoid cutting in poor weather.” Maize trash may also improve water absorption


“In the USA, mulching is also used to reduce soil erosion – trash is ploughed in or chisel ploughed after harvest to open up the soil and increase soil organic matter.”


The machinery used for harvesting is also not as heavy so the risk of compaction is less.

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