8Weed controlMaize seedlings struggle to compete with other plants, such as weeds or volunteersfrom previous crops. Weed control during the first six weeks after sowing is crucial.Herbicides and inter-row hoeing are the mainforms of weed control.Spray earlyA Maize Growers Association (MGA) weed controltrial showed that treating weeds early (within twoweeks of crop emergence) resulted in low levels ofcompetition and yields similar to all-season weedcontrol. Leaving weed control to six weekspost-emergence resulted in significant cropyield reductions.Figure 2: MGA weed control timing trialCompetition is most damaging during the first sixweeks post-emergence. Weed control carried outat this stage will kill weeds before they impact oncrop performance.• Pre-emergenceResidual herbicides are sprayed onto the drilledseedbed to remove any weeds that germinatealongside the maize. This approach gives the maizea head start.• Post-emergenceMost fields require a second, early post-emergenceherbicide spray, when the crop has one to threeleaves. This tackles the second flush of weeds.Delaying this post-emergence application willreduce the final crop yield.Final maize yield (t/ha fresh weight)6463626160595857565554All season After Aftertwo weeks four weeksTiming of herbicide applicationAftersix weeksProduct choice should be based on the weedspresent and those expected to germinate over thecoming weeks. Seek advice from a BASIS qualifiedadvisor and follow best practice application toprotect watercourses and the wider environment.The Voluntary Initiative has further guidancewww.voluntaryinitiative. org.uk.Changing pesticide regulationsFrom 2014, farmers have had to demonstratetheir use of Integrated Pest Management (IPM)with regard to chemical applications.From 26 November 2015, all sprayer operatorsare required to have the relevant certification toapply pesticides (including those previously exemptdue to grandfather rights). By 26 November 2016,all working application equipment must have aNational Sprayer Testing Scheme certificate.
9Crop nutritionFields to be drilled with maize are suitable for organic manure applications –either farmyard manure or slurry.To manage nutrients effectively, first send offrelevant soil and manure samples to a laboratoryfor nutrient analysis. Use this information, alongwith crop requirement recommendations, calculatedfrom Fertiliser Manual (RB209), to determinemanure application rate and the amount of anyadditional fertiliser needed.Time nutrient applications to coincide with cropgrowth to maximise uptake. Splitting therecommendations into lower rates will enablethe soil to retain nutrients better.Maize has poor tolerance of acidic soils (6.56-6.500 Apply 50-100kg/ha every three to four years wheresugar beet and potatoes do not feature in the rotationTo convert ‘kg per ha’ to ‘units per acre’ multiply by 0.8. So 50kg per ha x 0.8 = 40 units per acre.
10NitrogenSoil nitrogen supply (SNS) cannot be easilymeasured, so fields are put into categoriesdepending on their cropping history to estimatetheir likely requirement for N. Use the tables inthe Fertiliser Manual (RB209) to determine theSNS index of any field.Where maize is grown continuously, N can buildup in the soil, particularly where organic manuresare spread regularly. Rotating with another crop,such as grass or potatoes, or planting an autumncrop after the maize has been harvested, can makethe most of any residual N.Seek the advice of a FACTS qualified adviser fordetailed crop nutrition advice. Tried and Tested andother online tools are available to help develop anutrient management plan.Managing nutrients in NitrateVulnerable Zones (NVZs)Managing nutrients effectively is important for allfarmers growing maize, but there are statutory limitsfor those within a NVZ. On these farms, themaximum limit (Nmax) for maize is 150kg N/ha(120 units N/acre).The Nmax must account for all organic manuresapplied and the amount of crop available N presentmust be established.From the end of the closed period (see Table 3)to the end of February, no more than 30m 3 /ha(12m 3 /acre) of slurry or 8t/ha (3t/acre) of poultrymanure can be applied in a single application, withat least three weeks between individual applications.NB: This does not apply to newly designated NVZsuntil 2016.Manure applied at25m 3 /haDetailed guidance can be found atwww.gov.uk/nitrate-vulnerable-zones.Table 3: Closed periods for nutrient applicationNutrient Sandy or shallow soils Other soilsManufactured nitrogen 1 Sept to 15 Jan 1 Sept to 15 JanOrganic manures, high in readily available nitrogen,eg slurry, poultry manure1 Aug to 31 Dec 1 Oct to 31 Jan!Soil protectionGrowing maize is a high-risk activity withregard to the environment and requires moremeasures for cross compliance than other crops.These may include land drainage, use ofearly-maturing varieties, cultivating acrossa slope, using low ground pressure tyres,introducing a cover crop or undersowing.
11Avoid nutrient overloadNutrient application rates should be matched to crop requirements to avoid ‘nutrient overload’.Surplus nutrients can be lost to the environment via direct runoff into surface water or leaching intoground water. Rapid incorporation of freshly spread manure will help make the most of the N content.Low emission spreading equipment such as slurry injection reduces ammonia losses.Table 4: The value of slurry to maizeNitrogen(N)Phosphate(P)Potash(K)Maize requirement (kg/ha) a 50 55 175Total nutrients supplied by 30m 3 /ha cattle slurry application (kg/ha) 78 36 96Crop available nutrients (kg/ha) b 36 18 86Manufactured fertiliser required 14 37 89Slurry value in year one c £21.60 £14.40 £51.60Total slurry value (per hectare) £87.60aBased on SNS Index 2, P Index 2 and K Index 2-, b Assuming 6% DM, not accounting for nutrient losses, c Assuming N = 90p/kg,P = 80p/kg, K = 60p/kgMANNER-NPK is a free programme available to determine the nutrient availability of manures and theirvalue for the following crop. It can be downloaded from www.planet4farmers.co.uk/manner.Winter field managementMaize fields can be a significant source of soilerosion. All maize fields must be actively managedto reduce the risk of soil, nutrient and agrochemicalloss to the environment during winter. Options foroverwinter management include:• Undersowing maize with a cover crop –typically ryegrassBroadcast the cover crop into the growing maizeas the leaves of the maize touch across the rows,this is typically, at the end of June/early July. Thisreduces the likelihood of the cover crop competingwith the maize in the early stages.Typical grass seed rates are 10-15kg per hectare(4-6kg per acre). The cover crop will green up soonafter harvest, using any surplus nutrients andreducing water and soil loss from the field. This isa useful way to establish grazing or cutting leys.• Cultivating the field immediately afterharvest to encourage water infiltrationResearch has shown that cultivated fields absorbmore water than those left unmanaged, so lessnutrients, sediment and agrochemicals are lost.• Establishing an autumn cropSowing winter crops, such as winter wheat, aftermaize may reduce the soil wash and erosion risk.
12Pests and diseasesThe threat posed by pests and diseases to maize can be split into those thataffect the seed and those that attack the growing plant. The most potentiallydamaging pests are wireworm and maize eyespot.Table 5: Maize seed/seedling problemsPest damage Risk factors How to minimisethe riskControl optionsBirdsCrows inparticular liketo feed onmaize seeds.Shallowsowing depth.Bury seeds well.Treat seed withbird repellent.Employ traditionalbird scaringtechniques.WirewormLarvae feedon growingseedlings.Previouslyundisturbedgrassland.South-facingfields.Insecticide seeddressing.Allow asubstantialbreak betweengrassland andmaize.Applicationof insecticideonce there aremore than 75wireworms/m 2 .Ploughing.Frit flySecondgenerationmaggots eatthe youngseedlingsin May andJune.Predominantlygrasslandareas.Leave aten-week gapbetween grassand drillingmaize.Treat withinsecticide ifmore than 10%of plants areattacked.
13Table 6: Maize plant problemsDisease Risk factors How to minimisethe riskControl optionsMaize eyespot(Kabatiella zeae)First seen as spotting onthe leaf. When the spotsare held up to the light ayellow halo can be seenaround each one.Wet cool conditions.Non-inversion cultivationtechniques, eg min-till.Proximity to fields withmaize crop residues.Two or more years of maizecultivation.Plough maizestubble.Drill late into awarm seedbed.Rotate the maizecrop with othercrops.Fungicide treatmentas soon as diseaseis identified, plussecond treatment ifconditions remainwet/cold.Disease stops attemperatures above27°C.Fusarium mouldMould populations canbuild in maize and pose areal threat to a followingwinter cereal.Repeated maize cropping.Previous wheat cropping.Exposure to crop residuesand stubble.Grow maize inrotation withgrass.Do not rotatewith wheat.No fungicidesavailable.Remove or burycrop residues.Eyespot lesionsStem fusariumSeek advice from a BASIS qualified agronomist as to the most appropriatetreatment for any crop pest or disease.
16Feed valueMaize silage feed characteristics:• High energy, high starch• Cattle and sheep adapt to it easily in rations• Palatable• Consistent feed value• Low protein content so should be fed withreasonably high-protein feedsCattle given rationscontaining maize silagetend to have a higherdry matter intake (DMI),than those fed rationsbased solely on grasssilage. Offering a mixture of maize and grass silagealso increases DMI compared to grass silage alone.This extra DMI leads to higher energy intakes andwhen offered as part of a balanced diet, shouldimprove daily performance and feed efficiency.The digestibility of maize remains fairlyconsistent throughout the growing season. Asthe crop matures, the quality of stem and leafdeclines, but this is offset by the increase in grainin the cob, which is highly digestible and high instarch. This is why harvesting at the correct stageis essential to maximise nutritional value.Generally, mineral content of maize silage isrelatively low, so supplementation is required.Check with a mineral supplier/nutritionist forappropriate specifications to add to maize-baseddiets for cattle and sheep.Table 9: Feed values for different foragesFeed type Dry matter % Metabolisable Crude protein Starch % in DMenergy MJ/kg DM % in DMMaize silage 28-35 10.8-11.7 8-9 25-35Grass silage – first cut 22-32 10.5-11.5 11-15 –Fermented wholecrop 30-45 10-11.5 9-17* 15-22cereals*Crude protein may be higher for cereals grown with bi-crops (eg peas, clover, vetches)Table 10: Factors affecting the yield and feeding value of maize silageKey:PositiveNegativeHarvest too earlyHarvest too lateCutting height >90cmCutting height
17Silage analysisHaving an accurate nutritional analysis of conservedforages is essential when formulating rations, sothat they are used appropriately, accurately andcost-effectively.Six weeks after harvesting, take several core samplesfrom the clamp for testing. Continue to test samplesfrom the clamp face throughout the season asfeed value continues to change in the monthsafter harvest.A list of companies offering forage analysescan be found on the EBLEX BRP websitewww.eblex.org.uk.Maize grainIn southern England and the Midlands, maize grain is increasingly being grownfor crimping or whole cob maize, also known as ground ear maize (GEM).This is ensiled to feed as a concentrate, eitherconventionally combined with a maize ‘header’, orthe whole cob is foraged through a forage harvester.The optimum DM content of the grain forcrimping at harvest is 65-70% and 60-65% forGEM, which is higher than for maize silage.Therefore, harvest is typically three to five weekslater, which further restricts the areas where itcan be grown. Choosing an early maturingvariety is essential. Grain yield and standingpower are also important characteristics to lookfor when buying seed.The process of crimping or ‘milling’ through a foragerfor GEM, breaks the outer seed coat of the kernel andreduces the particle size. This increases its digestibilityand reduces any loss of grain through poor digestion.Maize grain contains more starch and energythan other cereal grains and also has a relativelyhigh level of bypass starch. This travels throughthe rumen undegraded and is digested furtherdown the digestive tract. This reduces the speedof fermentation and minimises possible dietaryupset in a mixed cereal diet.As with maize silage, additional protein – inparticular effective rumen degradable protein(ERDP), is required to provide a well-balanceddiet, along with a source of ‘long’ fibre topromote healthy rumen function.Table 11: Nutritional composition of differenttypes of maize feedMetabolisableenergy(ME/kg DM)CrimpedmaizegrainGroundearmaizeMaizesilage13.8-14.3 12.3-12.6 10.8-11.7Crude protein(% in DM)9-10.5 8.5-9 8-9Starch(% in DM)65-70 55-60 25-35DM (%) 65-70 60-65 28-35
18Feeding principles for beef cattleFinishing cattleThe high starch and energy of maize silage makes it ideal for finishing cattle.• For continental and/or dairy-cross finishing steers, maize silage can be the sole forage source• For finishing heifers and native-bred steers, it can be mixed with other lower metabolisable energyforages such as grass silage, whole-crop silage or straw to prevent unwanted fat depositionDry suckler cowsThe metabolisable energy levels of maize silage are too high to be fed ad-lib or as the sole foragesource for dry suckler cows.• Maize can be included in a mixed-forage or straw-based ration for dry cows. It is important to know theirmaintenance requirements and monitor body condition to prevent them becoming over-fatLactating cowsMaize can form a substantial part of a diet for autumn and late winter/early spring-calved cows withcalves at foot, in early to mid-lactation. During this phase, nutritional demand is high, virtually doublethat of a dry cow and maize can provide a useful energy source.Protein supplementationSince maize silage has a relatively low protein content, it does need supplementation with aprotein source when fed to cattle. This should be in the form of high effective rumen degradableprotein (ERDP) to improve starch and fibre utilisation. Sources of ERDP include rapeseed meal,pot ale syrup, beans, dried distillers’ grains or feed grade urea (either included in a molassed liquidfeed or as urea prills).Note: If using feed grade urea in any format, care must be taken to introduce it to cattle slowly.Measure amounts carefully and accurately and mix into the ration thoroughly. If in any doubtseek professional nutritional advice. Do not feed urea to cattle less than three months of age.
19Table 12: Example maize rations for cattleGrowing(300kg starting weight)Finishing(500kg starting weight)Liveweight growth target (kg/day) 0.8 to 1.0 1.3 to 1.5Grass silage (kg fresh) 15 4Maize silage (kg fresh) 7.5 12.0Rolled barley (kg) 1.0 6.0Rapeseed meal (kg) 0.9 1.2Minerals (g) 90 100Maize can reduce concentrate usewithout compromising performanceIn a Harper Adams University trial, there was nosignificant difference in performance of beefbulls finished on a diet of 75% maize silage and25% concentrate, compared to those fed a dietof 50% maize silage and 50% concentrate.Other research has also demonstrated that maizesilage can reduce concentrate input. However,the effect depends on the amount and qualityof maize fed and the animals' DM intake.Co-product feedsMaize is versatile and can be used with a widerange of other feeds, including cereals,concentrates, co-products, liquid molasses-basedfeeds and root crops (such as stock-feedpotatoes, fodder beet, parsnips).Suitable co-products include:• Waste bread, biscuit and confectionary meals• Maize germ meals• Wet distillery, brewing and starch extractionby-products• Potato waste• Processing by-productsIt is important to compare co-products on a drymatter basis and to balance them with appropriatesources of protein and long fibre. Seek professionalnutritional advice if unsure about the best way todevise rations incorporating maize withco-products and other types of feed.Carcase qualityInclusion of maize silage in a finishing rationincreases the white/creamy colour of thecarcase fat, compared to cattle fed diets basedon grazed or conserved grass. This is becausemaize contains fewer carotenoids than grass.
20Feeding principles for sheepMaize silage can work well as part of a ration for stock that require high-energy feed, ie ewes carryingmultiples in late pregnancy, ewes in early lactation and finishing lambs. It is less suitable for ewes inearly to mid-pregnancy and those carrying singles, because they may become too fat.When feeding maize silage:• Balance with high protein feeds. Make sure ewes close to lambing areoffered enough digestible undegradable protein (DUP)• Provide additional minerals, particularly calcium and trace elements, asmaize has low mineral content. Use an appropriate product for sheep• Check body condition score (BCS) regularly• Ask the vet to blood test a sample of ewes three to four weeks before theystart lambing to check energy and protein levels. Adjust ration if requiredTable 13: Example maize rations for ewes70kg Mule ewesTwins (kg fresh weight feed)Weeks before lambing8 6 4 2 1Grass silage* 3 3 3 2.7 2.7Maize silage 1 1 1 1 1Home-mix or compound feed - - 0.2 0.4 0.5Triplets (kg fresh weight feed)Grass silage* 3 3 2.8 2.6 2.5Maize silage 1 1 1 1 1Home mix or compound feed - 0.1 0.3 0.6 0.7*Assumes grass silage of 10.5 MJ/kg DM, 30% DM and 13% crude protein (CP). Compound feed 12.5 MJ/kg DM and 18% protein.The DMI of ewes will vary as lambing approaches due to increasing lamb size. This also occurs if the dry matter of the forage or choplength were to change. Monitoring intakes and adjusting the ration according to ewe appetite is recommended for optimum results.Maize rations for store lambsBelow is an example maize silage diet for store lambs weighing 30 to 40kg, aiming to grow at200g/day.Ad-lib maize silage (estimated intake of about 3 to 3.5kg fresh weight/day)+Protein supplement of up to 0.2kg of a 34%+ crude protein supplement, eg rapeseed meal,distillers’ grains, protein concentrate or a protein-molassed liquid feed+Appropriate minerals
21CostingsIn 2014, maize cost in the region of £1200/ha(£500/acre) to grow, including a rental value of£250/ha (£100/acre).*Here are the example costings for maize silageand maize silage sown under plastic comparedto grazed grass and grass silage.Grazed grass(Ten year ley)Grass silageThree cuts(Seven year ley)Maize silageMaize (plastic)Yield of fresh matter (t/ha) 58 50 42 52Typical dry matter content of crop % 18 25 30 30Yield of dry matter (t/ha) 10.4 12.5 12.6 15.6Establishment costs (£/ha)Ploughing 55 55 55 55Cultivations 70 70 70 70Sowing 30 30 45 45Seed 175 175 175 175Lime 60 60 60 60Fertiliser 1 55 55 209 209Sprays 26 26 45 45Fertiliser applications 10 10 20 20Spraying 12 12 24 24Additional cost of plastic 297Total 49 2 70 2 703 1000Additional annual costs (£/ha)Fertiliser 1 196 363 0 0Sprays 10 10 0 0Fertiliser applications 60 60 0 0Spray applications 12 12 0 0Harvest and sheets etc 0 420 170 170Rent (£/ha) 250 250 250 250Total annual cost £ per ha (£/acre) 577 (234) 1185 (480) 1123 (454) 1420 (575)Cost per tonne of DM 55 95 89 91Notes: 1 Purchased fertiliser price assumptions: N=85p/kg, P=66p/kg, K=45p/kg. 2 Total establishment costs divided by ley duration.* Figures produced by John Morgan, Creedy Associates
Other BRP publications availableJoint Beef and Sheep BRPManual 1 – Improving Pasture for Better ReturnsManual 2 – Improved Costings for Better ReturnsManual 3 – Improving Soils for Better ReturnsManual 4 – Managing Clover for Better ReturnsManual 5 – Making Grass Silage for Better ReturnsManual 6 – Using Brassicas for Better ReturnsManual 7 – Managing Nutrients for Better ReturnsManual 8 – Planning Grazing Strategies for Better ReturnsManual 9 – Minimising Carcase Losses for Better ReturnsManual 10 – Growing and Feeding Maize Silage for Better ReturnsSee the EBLEX website www.eblex.org.uk for the full list ofBetter Returns Programme publications for beef and sheep producers.For more information contact:Better Returns ProgrammeEBLEXStoneleigh ParkKenilworthWarwickshireCV8 2TLEBLEX is a division of the Agriculture and HorticultureDevelopment Board (AHDB)© Agriculture and Horticulture Development Board 2014All rights reserved.Tel: 0870 241 8829Email: firstname.lastname@example.org