Best Management Practices for Growing Maize on Dairy Farms

<strong>Best</strong> <strong>Management</strong><strong>Practices</strong> <strong>for</strong> <strong>Growing</strong><strong>Maize</strong> on Dairy FarmsOperatingbestImprovingprofitabilityIncreasingdairyproductivityConsideringtheenvironment

AcknowledgementsThe project group gratefully acknowledge the individuals and organisationslisted below <strong>for</strong> the time, knowledge and/or funding they have contributed.FundingMAF Sustainable Farming FundDairy NZEnvironment WaikatoFoundation <strong>for</strong> Arable ResearchGenetic Technologies LTDAuthorsChris Glassey - Dairy NZGabriele Kaufler - Environment WaikatoMike Parker - Foundation <strong>for</strong> Arable ResearchAndrea Pearson - Foundation <strong>for</strong> Arable ResearchIan Williams - Genetic TechnologiesPaul Johnstone - Plant & Food ResearchDesign and PrintBNS Design & Print Ltd© Foundation <strong>for</strong> Arable Research (FAR)DISCLAIMERThis publication is copyright to the Foundation <strong>for</strong> Arable Research and may not be reproduced or copied in any <strong>for</strong>m whatsoeverwithout written permission.This booklet is intended to provide accurate and adequate in<strong>for</strong>mation relating to the subject matters contained in it. It has beenprepared and made available to all persons and entities strictly on the basis that FAR, its researchers and authors are fully excludedfrom any liability <strong>for</strong> damages arising out of any reliance in part or in full upon any of the in<strong>for</strong>mation <strong>for</strong> any purpose. Noendorsement of named products is intended nor is any criticism of other alternative, but unnamed product.

<strong>Best</strong> <strong>Management</strong><strong>Practices</strong> <strong>for</strong> <strong>Growing</strong><strong>Maize</strong> on Dairy Farms“<strong>Maize</strong> is a vital crop <strong>for</strong> many New Zealand dairy farmers; it also represents asignificant investment in time and resources. This booklet aims to give farmers thetools that they need to extract maximum value from this investment, providing the mosttopical in<strong>for</strong>mation on maize crop preparation, management and harvest, in one easyto access resource.”Contents1. Improving pastoral dairy farming using maize silage ....................22. Liaising with your contractor and technical advisor ......................53. The drivers of maize yield ..............................................................74. Site selection ..................................................................................95. Soil preparation ............................................................................106. <strong>Maize</strong> nutrient requirements ........................................................127. Crop monitoring ...........................................................................158. Harvest and post-harvest management ......................................189. <strong>Maize</strong> <strong>for</strong>age trading code of practice .........................................2010. Record keeping ............................................................................2111. Resources and further in<strong>for</strong>mation ..............................................2212. Glossary .......................................................................................23Published by Foundation <strong>for</strong> Arable Research (FAR) September 2009Tel: 03 325 6353 www.far.org.nzISBN: 978-0-9864533-3-5Version 1 - September 20091

1. Improving pastoraldairy farming usingmaize silage<strong>Maize</strong> grown on dairy farmsCan:• Add value to a farms feedsupply• Help mitigate climatic risk• Extract excess soil nutrientsfrom high fertility effluentpaddocksMust be:• Fed to fill genuine feed deficits<strong>for</strong> economic responses• Well managed to reduce feedcosts and wastagePasture is the major component of the NZdairy herd’s diet; however, opportunitiesexist to improve profit through the strategicuse of maize silage.The pastoral dairy farm is a balancebetween pasture supply and cow demand,which must be maintained to achieveefficient conversion of feed into milk andprofit. Unless well integrated with pasturesupply and feed demand, extra feeds suchas maize silage, will produce extra milk, butnot always extra profit.To use maize silage profitability farmersmust identify what they are trying to achievethrough its use. This requires working outthe key limiting factors <strong>for</strong> running an efficientand profitable grass-based systemand whether changes are in line with theirgoals. This can be done in conjunction witha farm consultant or <strong>for</strong>age specialist.Important factors <strong>for</strong> improving pastoraldairy farming using maize silage are:1. Ensure that the highest responsesare gained from the feed eatenA key driver of response to additional feedis energy deficit, the difference betweenenergy demand and the actual energysupplied.Cows of high breeding worth ($BW), athigh stocking rates and with lactationslonger than 260 days, are more likely to bein energy deficit, and will be more responsiveto additional feeds such as maizesilage. Cows respond best to extra feed ifthe farm has a genuine feed deficit, createdthrough calving earlier, more days in milk orcarrying more cows per hectare.If all of the additional energy provided bysupplement is converted into milk, themaximum possible response is 13 g MS/MJ metabolisable energy (ME). This isequivalent to 137 g MS/kg DM maize silage(assuming maize silage is 10.5 MJ ME/kgDM). In practice, responses are usuallymuch lower than this due to feed lossesin transport, storage and feeding, the substitutionof supplement <strong>for</strong> pasture, thepartitioning of energy into liveweight gain(LWG) or the maintenance of extra cows.Trials in New Zealand have found productionresponses to maize silage between 32g MS/kg DM and 178 g MS/kg DM. Thehighest response came from more daysin milk created by feeding maize silage ina year affected by a dry summer. Analysisof more than 600 NZ dairy farms found onaverage, that supplements fed added only50 g MS/kg DM to annual milk solids percow and 96 g MS/kg DM to annual milksolids/ha. With such a variation in responsepossible, attention to detail is required inorder to turn additional feed into additionalprofit.2

6. Use maize silage to re-grasspaddocks<strong>Maize</strong> silage acts as a “break crop” <strong>for</strong> controllingperennial weeds such as couch andkikuyu, as well as reducing the populationsof the clover root knot nematode and thewhite fringed weevil.In summary, growing maize on dairy farmscan be an important component of plannedimprovement of a farm’s feed supply, eitherdirectly through the high potential DM yieldof the maize crop itself and/or through theimproved pasture resulting from a plannedcropping rotation.4

2. Liaising with yourcontractor and technicaladvisor<strong>Growing</strong> maize requires a rangeof operations:• Most dairy farmers will needcontractors to assist with someor all of these processes• Some contractors and technicaladvisors will offer a cropmanagement service• Communication and goodplanning are key to working withcontractors and technicaladvisors<strong>Growing</strong> maize requires a range of operationsfrom cultivation through to harvest.Most dairy farmers won’t have the specialistequipment required <strong>for</strong> growing maizeand will there<strong>for</strong>e need to employ contractors<strong>for</strong> these tasks.For those with limited time or experience,technical advisors from a range of merchantcompanies are available to offer crop managementservices and/or advice. There arespecialist contractors and advisors whoconcentrate on only one aspect of maizeproduction (e.g. spraying or fertilisers).Others provide a complete service fromsowing to harvest.The key to working with contractors andtechnical advisors is good communication.Most have several hundred clients requiringthe same service at much the same time.Notice of your intentions well in advanceand then regular updates will improve theservice they can provide. You will needto talk with your contractor and technicaladvisor regarding your specific requirements,which may include:1. SprayingYour spray contractor will need to knowyour sowing date so that they can planwhen to spray out pasture, and later whenherbicides will be required <strong>for</strong> the crop.Monitoring (chapter seven) will help determineif post emergence herbicides will beneeded.2. CultivationYour cultivation contractor can adviseand outline costs of cultivation methods;however, this will need to be done well inadvance of the projected planting date.(chapter five – Soil Preparation)3. SowingYour sowing contractor will need advancewarning of both your intended sowingdate and your fertiliser program. SeedCompanies and Rural Supply firms will giveadvice on a suitable maize hybrid <strong>for</strong> yoursite, sowing date and planned harvest date.You should also discuss options regardingseed treatment <strong>for</strong> pest control.4. FertiliserEnsure you have a recent soil test, collectedfrom 0-15 cm deep from your intendedmaize paddock. Paddocks coming out oflong term pasture can supply up to 300kg N/ha just from soil organic matter, sosoil test <strong>for</strong> mineral nitrogen (0-60 cm) todetermine post sowing urea applications.Technical advisors and fertiliser companiescan organise soil tests and develop fertiliserplans. (chapter seven - Crop Monitoring).There are a number of different methods offertiliser application; bulk spreader <strong>for</strong> basefertiliser, sowing contractor <strong>for</strong> fertiliser5

applied through the drill, post emergence N- often referred to as side-dressing (knifingor broadcasting urea into the soil six toeight weeks after sowing). Your technicaladvisor will assist you in determining thebest method <strong>for</strong> your conditions. (chaptersix <strong>Maize</strong> Nutrients)5. Harvesting<strong>Maize</strong> harvesting and stack building is anextremely busy and difficult time <strong>for</strong> contractors;with large hectares to harvest, ashort time frame and often adverse weatherto contend with.<strong>Maize</strong> is normally harvested between 30 to40% dry matter. Let your contractor knowyour preference well in advance.Determining maize silage maturity in thefield requires considerable experience.Generally harvest contractors will monitorcrop maturity and determine harvest time.Technical advisors will also give guidance ifrequired. (chapter seven)Remember that stack sites and accessareas must be prepared be<strong>for</strong>e harvest.Aim to get this done early in case the cropmatures faster than expected.Post harvest planning e.g. sowing newpastures, is also crucial to continuedsuccess. Again your technical representativewill be able to assist you with the bestoptions <strong>for</strong> your site.6

3. The drivers of maizeyield<strong>Maize</strong> yield is affected by manyfactors:• Sowing location, sowing date,hybrid choice and population willall influence the potential yield ofthe crop• Potential yield can be reducedby weed and pest presence,moisture stress, disease andnutrient limitations<strong>Maize</strong> crops behave in a very predictablemanner, making it a very attractive crop<strong>for</strong> researchers to work with. There<strong>for</strong>e thedrivers of maize yield are well understood.Potential yield (the maximum possibleyield provided there are no limitations dueto; weed pressure, drought, water logging,nutrients, disease, and soil structure etc) isdriven by radiation interception.Radiation (sunshine energy) is absorbedby the crop according to how much iscoming in, and how much green leaf areais available to intercept it. The radiationis converted to biomass at a rate of 1.6 TDM/ha <strong>for</strong> every 100 MJ of radiation intercepted.<strong>Maize</strong> is one of the most efficientplants at doing this.Temperature is another factor which alsoinfluences potential yield, because it affectsthe rate of development (time to variousgrowth stages like leaf emergence andsilking). Temperature is used to calculate‘<strong>Growing</strong> Degree Days’ (GDD’s). Warmertemperatures mean crops reach maturityfaster.To maximise potential yield, we need tomaximise radiation interception. There arefour main factors that drive this; location,sowing time, hybrid and population.1. LocationTemperature and radiation are differentaround the country. The highest maize yieldsare often achieved in Gisborne, because ofthe high radiation and long growing seasonin that region. Often our growing locationis fixed, but if you are thinking of leasing orbuying land to grow maize on, you shouldinvestigate the climatic conditions at thesite.2. Sowing timeThis affects radiation interception, as radiationchanges during the year. Radiationpeaks in late December, so aim to sow yourcrop so that you have full canopy coverby this stage, to maximise the use of thisradiation.In general, earlier sown crops tend to yieldbetter than later sown crops (Figure 1).However sowing time needs to be balancedagainst many other factors such as; frostrisk, soil conditions and any pasture silagethat you wish to harvest off the paddock.Figure 1. Effect of sowing time on potential yield<strong>for</strong> a medium season maize silage crop grown inthe Waikato.7

3. HybridThere are many different maize hybridsavailable. The main differences betweenhybrids are:• The number and size of leaves (whichaffects green leaf area and henceradiation interception).• Crop maturity or the number of GDD’sbe<strong>for</strong>e the crop is ready to harvest.• Their ability to cope with stresses suchas disease or drought.Your choice of hybrid will ultimately dependon; where you are, when you want to sow,and when you want to harvest. Your seedsales representative can help you select asuitable hybrid.As a general guide, short season hybridstend to yield less because they have fewerand smaller leaves than long seasonhybrids (intercept less radiation). They alsoneed fewer GDD’s to reach maturity, sothey are in the ground <strong>for</strong> fewer days, andhence absorb less radiation.4. Plant populationPopulation affects radiation interception asmore plants means more leaf area. Typicalpopulations <strong>for</strong> maize silage is 100 to 120thousand (K) seeds per hectare (there are80 K seeds in a bag) and your seed salesrepresentative will advise you on the bestpopulation <strong>for</strong> your situation. Final populationsare normally 5 K/ha less than whatwas originally sown.Other factors affecting potential yieldPotential yield assumes there is no limitationto the stresses that commonly affectmaize yields. In reality, this is seldom true.Weed pressure can reduce maize yield byup to 30%, make harvest difficult and contaminatesilage. Monitor crops <strong>for</strong> weedsand take action early as many weeds cangrow faster than maize seedlings.Drought will reduce maize yield by 22 kgDM/ha <strong>for</strong> every 1 mm of potential soilmoisture deficit (the difference betweenwhat a crop needs and what it gets).Because maize has deep roots (up to 1.8m), few maize crops are irrigated exceptif grown in dry environments and/or onshallow soils.Water logging reduces the plant’s abilityto take up nutrients, and creates a toxic soilenvironment <strong>for</strong> plant roots, since the soilcannot ‘breathe’ and release gases createdby soil microbial activity. Prolonged waterlogging can cause large losses in maizeyields.The nutrient requirements <strong>for</strong> maize willbe covered in chapter six. The nutrientmost likely to limit maize yields is nitrogen.Soil nitrogen is generally low in paddockswith a long history of cropping, but veryhigh in paddocks coming out of long termpasture.The main leaf diseases of maize arecommon rust, eyespot and northern cornleaf blight. Severe infection can reduceyields by 30%. Only in very disease proneconditions (warm and humid, together witha hybrid of lower disease resistance) willthe application of fungicides be economicallybeneficial.Pests can also affect yield. Argentine StemWeevil (ASW), Greasy Cutworm and BlackBeetle can be a problem particularly ifdirect drilling or strip tilling. (chapter seven- Crop Monitoring)Soil structure tends to deteriorate withrepeated cultivation. Compaction reducessoil aeration and aggregation, affecting theability of plant roots to extract water andnutrients from the soil. Paddocks <strong>for</strong>merlyin long term pasture generally have goodsoil structure.8

4. Site selection• Paddock selection is important interms of:- Access <strong>for</strong> large maizemachinery- Yield potential- Cost of production and harvest- Environmental impacts• Consult with your contractor(s)be<strong>for</strong>e finalising your siteselectionMany dairy farmers use maize grown onfarm as part of their pasture renewal programme.However, not all such paddocksare suited <strong>for</strong> maize production.• Very steep paddocks (often also withwetter gullies) not only make cultivationand harvesting difficult and hazardous,but also tend to not yield as well.• Low lying wetter paddocks will oftenmean delays in cultivation after adverseweather. Again these often do not yieldas well, unless drought conditionsprevail.• A paddock which is wet with a grasssward, acts as if 10% wetter when thestructural strength of the sward isremoved by cultivation.• Wet paddocks risk a loss of soilstructure under cultivation which in turnleads to lower yields.Many long term effluent paddocks have highN and K levels and there<strong>for</strong>e are ideal <strong>for</strong>growing a deep rooting crop of maize oftenwithout using any bagged fertiliser (chaptersix). While this often means herds have towalk further while the effluent paddock isout of rotation, the opportunity <strong>for</strong> reducedgrowing costs and environmental benefitsshould be considered. Many long termdairy pastures also have a fertility level thatmeans N fertiliser inputs <strong>for</strong> maize cropssown from pasture can be reduced withoutmaize yield reductions.It is also important to consider the locationin terms of protection of sensitive areasi.e. streams, lakes, wetlands and drains(chapter five)To grow high quality maize silage on farm<strong>for</strong> the least cost, consider the factorsthat make a contractor’s job speedy andefficient.Paddock access is also very important,the distance from the paddock to stackwill reflect in the harvest cost. Cartagecosts from distant runoffs will be greatest;however narrow, rough farm tracks withpoor access will also mean higher costs.<strong>Maize</strong> cultivation equipment and harvestersare wide, long, and heavy, requiring gatewidths of at least 4 m with ample turningroom, unless fences can be dropped.Bridges or culvert crossings need to beof sufficient strength to hold the weight ofheavy vehicles and (at harvest) their loads.Low hanging overhead wires should beraised, or at least temporarily removed.Consult your contractor prior to finalisingyour site they can assist you in selectingthe best paddock to sow in maize.9

5. Soil preparation• The soil provides water andnutrients to the crop, but poorlymanaged cultivation can damagesoil and affect crop yields• Factors to consider are:- Soil type and suitability <strong>for</strong>cultivation- Adjacent sensitive areas (e.g.waterways)- Quality of the final seed bed(uni<strong>for</strong>mity of surface andaggregate size)- Intensity of cultivation, includingthe pros and cons of ploughingThe soil provides water and nutrients <strong>for</strong>plant growth; there<strong>for</strong>e, a healthy (structurallysound and biologically active) soil isimportant <strong>for</strong> crop production.Cultivation serves many purposes in cropestablishment.• Creating a uni<strong>for</strong>m seed bed• Relieving compaction (e.g. from stocktreading) and improving aeration• Incorporating residues and weeds• Warming and drying the soil• Incorporating lime and fertilisersPoorly timed or managed cultivation candamage soil, cause compaction anderosion problems, and ultimately affectcrop production. This is most likely to occurwhen the soil is too wet or too dry.Some of the key steps <strong>for</strong> successful cultivationare outlined here:1. Understand your soil resourceHow your soil responds to cultivationwill depend on the soil type and texture,plus any limitations it may have such asrisk of erosion and water logging. Yourregional council can help you to identifyyour soil type and any limitations it has <strong>for</strong>cropping.2. Identify sensitive areasSoil can run off into water ways during highrainfall events, creating erosion and waterquality issues. Most regional councils haveguidelines <strong>for</strong> how close you can cultivateto a waterway. If you need to leave a bufferzone around the edge of your cultivatedzone, don’t spray it out as weeds will establishinstead. Rank grass vegetation will actas a filter and help trap potential run off.3. Soil surface<strong>Maize</strong> seed is normally sown around 5 cmdeep. An uneven soil surface (undulations,ruts etc) makes it difficult <strong>for</strong> the planter toplace the seed at a uni<strong>for</strong>m depth, resultingin variable emergence. Very cloddysoil or large ruts can cause the planter tobounce, causing variability in seed depthand spacing.4. Aggregate size<strong>Maize</strong> does not need a very fine seedbed.It is a large seed and seed to soil contact isgenerally sufficient <strong>for</strong> germination, exceptin very cloddy soils. Light rolling aftersowing may help improve the seed-soilcontact, seal in moisture and reduce therisk of wind erosion.5. Minimal cultivationExcessive cultivation weakens the soil andaccelerates loss of soil organic matter.Keep cultivation to a minimum and avoidcultivation when the soil is too wet or too dry.10

6. Should I plough?Ploughing is a quick effective way to buryplant residues that might otherwise impedesecondary cultivation or cause weedproblems. However a comment we oftenhear from dairy farmers is that maize is ‘hardon the soil’ and one of the main causes ofthis is associated with ploughing.Pastoral farmers invest a lot of money infertiliser to improve the nutrient levels inthe top 7.5 cm of their soil. If that topsoilis then buried at 20 cm by ploughing, thensubsequent soil tests will show lower fertility.Those nutrients are still there but nowbelow the 7.5 cm soil sampling depth andout of reach of the new grass trying toestablish after maize.Talk with your contractor about alternativesto ploughing, such a discing. Be aware thatyou may need a longer fallow period (timebetween spraying out pasture and firstcultivation pass), but you need to balancethis against the long term damage to yoursoil fertility. Conversely, ploughing may bea remedial option if your topsoil nutrientsare too high (chapter six).There are other reduced tillage options<strong>for</strong> maize such as strip tillage and directdrilling, but these require more attentionto details and are best suited <strong>for</strong> specialistmaize growers.11

6. <strong>Maize</strong> nutrientrequirements• <strong>Maize</strong> requires substantialnitrogen (N) and potassium (K),both of which are present in largeamounts in dairy soils• Up to 300 kg N/ha is releasedfrom soil organic matter whenhigh fertility dairy pastures arecultivated• <strong>Maize</strong> is unlikely to respond to Kfertiliser unless soil K test levelsare very low. Replacement Kfertiliser can be applied afterharvest to avoid luxury uptake bythe maize crop• Soil test <strong>for</strong> N be<strong>for</strong>e applyingpost emergence N fertiliser todetermine if any is required• Dairy effluent can be used asa nutrient source <strong>for</strong> maize,provided that the crop requiresthe nutrients and good effluentmanagement practices arefollowedCropping and dairy farmers often havedifferent approaches to fertiliser management.Cropping farmers will estimate whatthe crop needs, measure how much isalready available, and then determine howmuch extra is needed. Pastoral farmers aremore focussed on reaching optimum levelsof soil fertility, then maintaining them usinga nutrient replacement policy.A nutrient replacement approach <strong>for</strong> maizegrown on dairy farms does not work well,<strong>for</strong> two main reasons.• <strong>Maize</strong> can access nutrients from rightthrough the soil profile, not just the top7.5 cm. Deeper nutrients are availableto maize but not to grass, so why notuse them?• Cultivation of pasture paddocksreleases large amounts of nutrient,particularly nitrogen.The upside of both is a huge saving in fertiliserinputs.1. Nutrient uptake by maize silageThe average maize silage crop containsabout 1.1% nitrogen (N), 0.2% phosphorus(P) and 1.2% potassium (K). This means amaize silage crop yielding 20 T DM/ha willtake up around 220 kg N, 40 kg P and 240kg K. It does not mean this is how muchfertiliser we need to apply. Let’s go througheach of these nutrients separatelyNitrogen (N)Of all the nutrients used on cropping farms,N is most likely to limit maize yields and istypically the largest fertiliser input. TypicalN inputs <strong>for</strong> maize would be 20-50 kg N/haapplied at sowing and around 100-200 kgN/ha applied as urea six to eight weeks later(post emergence N, sometimes referred toas side-dressing).These inputs are generally not needed <strong>for</strong>maize grown in dairy paddocks comingout of long term pasture. Over the pasttwo seasons, we have monitored maizegrown in nine dairy paddocks, both withand without a history of effluent application.Results have been consistent. Wefound no response to N fertiliser at any sitebecause we measured up to 300 kg N/hareleased by the soil, enough to meet croprequirements.You may still chose to apply a small amountof fertiliser at sowing, however, in the firstyear out of grass there is no need to applyfurther N fertiliser to maize crops grown indairy pastures. If in doubt, get your fertiliserrep to collect a deep N soil sample (60 cm)12

<strong>for</strong> mineral N be<strong>for</strong>e you apply any postemergence N. The AmaizeN N fertiliser<strong>for</strong>ecaster can help interpret the results.Phosphorus (P)How can such a huge crop use such asmall amount of P? Phosphorus is used byplants <strong>for</strong> root growth, nutrient uptake andgrain development. <strong>Maize</strong> is highly efficientat using P. The removal of 40 kg P/ha by amaize crop will barely register in a soil test.Your cultivation practices are likely to havea bigger impact (chapter five).Most growers apply a small amount of Pat sowing. Recent trials on maize silagegrown on dairy farms showed that eventhough the seedlings looked smaller whereno P fertiliser was used, there was no effecton final yield.How much P fertiliser you apply will dependon your soils’ Olsen P status and whetheryou want to increase, maintain or decreaseit. Discuss your long term plans <strong>for</strong> thepaddock with your fertiliser rep.Help, my crop has turned purple!!This purple discolouration sometimesseen in maize seedlings is often attributedto P deficiency, but is more likely due tosome other stress such as the cold orwet. Certain hybrids are more prone topurpling. In the vast majority of cases, thecrop will grow through the stress with nopermanent effects.Potassium (K)<strong>Maize</strong> silage is around 1.2% K (a 20 T DMcrop uses 240 kg K) but unless you havelow soil K levels (

3. Can I use dairy effluent <strong>for</strong>fertiliser?In short, yes. The ratio of NPK in maize issimilar to that found in dairy shed effluent,so they make a good match. Early resultssuggest that about half of the nutrientsapplied as effluent are available to themaize crop in the year of application.However, as with any fertiliser, we need toestablish whether the crop or soil requiresthese additional nutrients.If the paddock is just out of grass, thesoil can supply plenty of N and furtheradditions through effluent are probablynot needed. Paddocks with a history ofcropping (e.g. a dedicated cropping blockor run off) are most likely to benefit fromeffluent application.If you are applying effluent to your maizecrop, then follow good practice.• Test your effluent <strong>for</strong> nutrient contentprior to application, so you can calculatean appropriate application rate.However, be aware that this will be arough estimate as effluent nutrientcontent is highly variable. The maximumloading to cropping ground in theWaikato is 200 kg N/ha/year as effluent.• Check how much is actually applied.Put containers in the paddock duringapplication and measure the depth. Youcan multiply the volume applied by thenutrient content to determine how muchtotal nutrient was applied.• Ensure there is no ponding or run offduring application. You may need tomake multiple passes to apply theamount you want.cause metabolic problems in cattle. <strong>Maize</strong>can be successfully grown on effluentblocks with high soil fertility without the useof additional fertiliser.<strong>Maize</strong> will take up K from the soil and if it isfed out around the farm, then the nutrientswill be redistributed around the farm. If themaize is fed on a feed pad with wash downinto the effluent system, then the nutrientswill end up back on the effluent block.Soil cultivation associated with growinga maize crop can redistribute nutrientsthrough the soil. Ploughing will move topsoilnutrients to depth, so this may be an optionif your soil K levels are excessively high.4. <strong>Growing</strong> maize on the effluentblockLong term application of effluent increasessoil K levels. Pastures with high K levels can14

7. Crop monitoring• Monitoring is an important partof good management to maximiseyield• A good monitoring programmeshould include:- Weeds, pests and diseases- Soil N sampling- Soil moisture if irrigating- Crop maturity• Contractors and technicaladvisors can undertake someor all of this monitoringapplication, delayed application or perennialweeds can mean that further post emergenceapplications are required. Choice ofchemical will depend on what weeds arepresent and their growth stage, there<strong>for</strong>emonitoring is vital. Paddocks out of longterm pasture often have a greater broadleaf weed seed bank than grass weeds andthere<strong>for</strong>e omitting a grass weed herbicide(chloroacetamide) from the mix might beworthwhile. However, run out pastures oftenhave (<strong>for</strong> example) summer grass weedseed present and there<strong>for</strong>e the addition of achloroacetamide would be necessary.3. Emergence to four leaves (V4)In order to anticipate or rectify problemsand maximise yield it is necessary tomonitor crops regularly, particularly in thefirst two months of growth. For the busydairy farmer, technical advisors and somecontractors will provide this service.1. EmergencePaddocks need to be checked <strong>for</strong> slugs,bird, rabbit and rat damage. Slugs aregenerally not a problem where intensivecultivation has been carried out but cando serious damage during wet weatherand if reduced tillage practices have beenused. Leaf damage and slime trails are agood confirmation of slug presence. Birdand rat damage is characterised by plantspulled and the seed embryo eaten. Missedplanted rows or poor population areasshould be noted at this time and if practical,rectified.2. WeedsWeeds in maize crops can cause significantyield loss and moisture activated preemergenceherbicides generally per<strong>for</strong>mvery well. However, dry conditions afterNote four leaves with clearly visible collars.Continue monitoring <strong>for</strong> slug and birddamage but also to check <strong>for</strong> greasycutworm and weeds. Greasy cutwormfeed at night by typically cutting and fellingmaize plants. Their presence can be confirmedby digging around the base of freshlyfelled plants or examining plants near dusk.Spraying with a synthetic pyrethroid insecticideat dusk gives good control.Greasy cutworm15

Deep soil (0-60 cm) mineral N testing canalso be carried out while pest and weedmonitoring (chapter six) to plan post emergencefertiliser N application.4. Six leaves with visible collars (V6)From V6, the crop grows very rapidly andwith time eliminates vehicle access intothe crop. High clearance sprayers or aerialapplication become the only options.If further N fertiliser is required, thenmake sure it is applied by this growthstage. Monitoring can also be done duringfertiliser application and sometimes postemergenceherbicide applications are alsoapplied with the fertiliser.5. Mid to late DecemberLeaf diseases (if warm and humid) appearduring this time. Monitoring <strong>for</strong> commonrust, eyespot, and northern corn leaf blight(more common in long term maize land) isimportant if less resistant hybrids have beenused. Fungicides will give control but areseldom used unless environmental conditionsare particularly favourable to disease.Generally around the 20-30th December isthe time to check <strong>for</strong> army worm caterpillarespecially if crops are weedy. Note thatcorn earworm often appears in Januaryas the cobs are pollinated. They are generallycontrolled by parasitic wasps. Cornearworm should not be confused witharmyworm.Armyworm caterpillars - green, then greenishbrown when older.Corn earworm.6. IrrigationWhile generally not practised in most NorthIsland dairy regions, irrigation is common inCanterbury. Inadequate moisture (when thesoil moisture falls below half the soil waterholding capacity) at any growth stage canreduce maize yield. It is advisable to run awater budget or schedule based on 50%of plant available moisture linked to weekly16

evapotranspiration rates (ET). Moisturestress can also result in a lack of synchronisationbetween pollen shed and silking atpollination.7. Silking dateOne important maturity indicator is themaize kernel milkline, where the milkyliquid changes to the harder darker starchline. By simply snapping a cob in two andexamining the upper portion’s kernels, themilkline can be seen. When the milkline isone third of the way up from the bottom ofthe kernel the plant is in the 28 to 32% DMrange. However, other indicators need tobe considered (including those mentionedearlier) such as the hybrid, the husk covercolour, the greenness of the leaves andstem.Silking date is the date when 50% of the plantsare showing silk at the tip of the young embryoniccob.1/ 3 rd Liquid milkThe date when 50% of the plants are silking(refer to photo) should be noted. <strong>Maize</strong>generally takes 50-55 days from this timeto reach two thirds milkline, an importantindicator of crop maturity.<strong>Maize</strong> kernel milkline.2/ 3 rds Solid starch8. Three weeks prior to harvestIt is vital that crops are checked <strong>for</strong> harvestmaturity. The AmaizeN calculator and 50%silking date will greatly aid in determiningwhen to start frequent monitoring. Goodquality maize silage is best made when thewhole plant Dry Matter (DM) is between 30and 40 %. If harvested at less than 30%DM, silage in the stack will be wet resultingin high stack leachate, this leachate representsnutrient loss. If greater than 40%DM, stack compaction and air exclusion ismuch more difficult.In-field estimation of crop DM requiresconsiderable experience as; changes insoil type, topography, proximity to trees orhedges, the hybrids cob to stover (vegetativeparts) ratio and time of day, all need tobe taken into account. However, by examiningplants in representative areas goodestimates can be made.Most contractors and technical advisorshave experience in harvest scheduling.Dairy farmers would be wise to seek theiradvice in this area.17

8. Harvest and postharvestmanagement• Once ensiled maize silagedeteriorates when exposed to airTo minimise losses:- Carefully consider stacklocation and prepare the site inadvance of harvest- Design the stack to minimisethe amount of maize exposedwhile the stack is being fed out- Minimise disturbing ordamaging the stack face tomaintain compaction<strong>Maize</strong> silage is full of soluble carbohydratewhich while being a great food <strong>for</strong> cows, isalso loved by spoilage bugs, such as yeastsand moulds. Yeasts and moulds needoxygen to survive. The aim of the ensilingprocess is to get air out of the stack andkeep it out until the maize silage is readyto be fed.1. Storing maize silageChoosing a siteYou need to make sure that the stack is wellsited.• Locate it close to the area where themaize will be fed.• Ensure that it is far enough away frombanks, fences, walls and trees to allowtractors room to run off the stack whilethey are building it.• Choose an area which is free draining.• If you need to lay down a metal or limepad ensure that this is done in advanceand well compacted.• Bait the area with rat bait <strong>for</strong> at leasttwo weeks prior to the maize beingharvested.• Consider environmental implications, <strong>for</strong>example: pollution risk from runoff ofstack leachate, distance to waterways,drains and other sensitive areas.Stack typesOne issue to consider is to whether to usea bun (stack) or a bunker. Buns can belocated around the farm and are there<strong>for</strong>emore flexible, whereas bunkers are initiallymore expensive, BUT have higher compactionrates and there<strong>for</strong>e less wastageYour storage contractor will be able toassist on the best method <strong>for</strong> your farm.Building the stackStack dimension depends on how muchmaize you are going to stack, how manyanimals you have and what inoculant youare using. The aim is to build a stack sothat when being fed out, as little maize aspossible is exposed to air, <strong>for</strong> as short atime as possible. There<strong>for</strong>e, a taller stack isbetter than lower one and narrower stack isbetter than wider one. Ideally it should takeno more than three days to feed across thestack face, taking out about half a metreeach feed.As the stack is being built make sure thatthe maize is being layered no deeper than150 mm deep.Covering and sealingCover the stack with the highest qualitycover you can af<strong>for</strong>d, immediately after thecontractor has finished rolling the maizesilage. Seal around the base of the stackwith soil, sand or lime and place tyres overthe top of the stack. Ensure that there aresufficient tyres to cover the stack completely,with no gaps between the tyres.If birds are a problem, cover the wholeensiled stack with shade cloth, this is light,cheap and effective.18

2. Feeding out maize silageStarting feedingOpen the stack at the opposite end tothe prevailing wind to prevent air gettingpushed under the cover. Use a front endloader to create a face. Once the face hasbeen created, chip away from the top of thestack, rather than lifting up from the bottomof the stack face. Do not ram the bucketor silage <strong>for</strong>ks into the face of the stack asthis creates shatter and may allow air topenetrate into the maize stack.Heavy rainfall can also pose a risk if thewater gets into the stack creating a pollutionrisk through leachate.Face managementEnsure that the face is left tight daily, withno loose material at the base of the stack.A wide mouth shovel and a broom willhelp prevent this. You do not need to dropthe cover down over the face each day. Ifbirds are a problem use shade cloth or birdnetting to cover the face of the stack witha few tyres top and bottom to prevent thewind lifting it.Closing a stack downUse a front end loader to remove any loosematerial from the front of the stack, trimup the face using an old chainsaw, andthen spray a saturated salt solution overthe stack face. Drop the silage cover backdown over the face, reseal the base withsoil, and place tyres against the coveredface. Replenish all the bait stations aroundthe stack and leave the stack until you needto feed out again. It is a simple matter ofrolling the cover back up, removing anymaterial that may have become mouldyand feeding out again.19

9. <strong>Maize</strong> <strong>for</strong>age tradingcode of practice• The ‘<strong>Maize</strong> Forage Trading Codeof Practice’ has been designed tosafeguard both the buyer andseller of maize• Standard protocols <strong>for</strong> weighing,sampling and testing have beendeveloped <strong>for</strong> trading on a dryweight basis (kg DM)• These protocols can be used<strong>for</strong> determining the total DM yieldof your stack <strong>for</strong> feed budgetingpurposesIf you are buying or selling maize silage,you should be aware of the ‘<strong>Maize</strong> ForageTrading Code of Practice’, which has beendesigned to safeguard both the buyer andseller of maize. Developed by contractorsand industry groups, the code outlinesbest practice <strong>for</strong> trading maize <strong>for</strong>age on adry weight basis (i.e. kg DM).To ensure fair trading, the following in<strong>for</strong>mationis required:• Accurate weight of each truck load• Representative samples of <strong>for</strong>age fromeither trucks or the stack• Accurate analysis of DM content (%) ofthe samplesAfter extensive trials, a standard set ofweighing, sampling and testing protocolshave been developed. The protocols aredescribed fully in the code and are alsosummarised in the ‘Good Practice Guide<strong>for</strong> the Trading of <strong>Maize</strong> Forage’.Even if you are not trading, using thesampling protocols to determine the totalDM yield in your stack will be useful <strong>for</strong>feed budgeting purposes. As well asDM%, the samples can also be tested <strong>for</strong>feed quality or nutrient content.A recent addition to the code is a standardpurchase contract that can be used<strong>for</strong> trading maize <strong>for</strong>age. Recent marketvolatility has tested the value of a verbalarrangement, and a signed contract willallow parties to legally <strong>for</strong>malise theiragreement. To provide confidence, securityand stability <strong>for</strong> all parties, we strongly recommendthat a <strong>for</strong>mal purchase contractis used.The complete code, good practice guideand purchase contract are all availablefrom Foundation <strong>for</strong> Arable Research.While the code is focussed on maize <strong>for</strong>age,the same principles apply to other <strong>for</strong>agessuch as pasture or cereal silages.20

10. Record keeping• Crop management should berecorded <strong>for</strong> a number of reasons• You should make sure that youhave copies of crop managementrecords, even if a contractor ortechnical advisor is managingyour cropThere are numerous good reasons <strong>for</strong>keeping crop management records, theseinclude:Environmental reportingAll Fonterra suppliers are required tocomplete nutrient budgets and your maizesilage crop should be done as a separateblock.Financial reportingA ‘Cost of Production’ worksheet canassist you to calculate the cost of growingyour crop.DiagnosisIf something goes wrong with your crop.Repeat ResultsWhen you grow a fantastic crop, you willknow what was done so you can to do itagain!You may rely on others (e.g. technicaladvisors or a contractor) <strong>for</strong> some or allof your crop management. However, youshould still make sure you have copiesof crop management records. These willbe useful if your advisor changes, or youchange to another company or contractor.1. Crop management records tokeepLaboratory tests:Copies of any soil, plant and effluentanalyses including when, where and howthe samples were collected and by whom.CultivationWhen, how, who and any notable soil conditions(e.g. a bit dry, too wet).HerbicidesFor each application record; when, theproduct(s) used, chemical and water rate,who sprayed, and weather conditionsduring application (especially wind directionand speed).Nutrient inputsFor all fertiliser, lime, effluent or othernutrient inputs (e.g. chook manure), makesure you record when, where and how itwas applied, the rate and nutrient contentof the product, and who applied it.Crop detailsThe hybrid, sowing time, plant populationand any seed treatment used.Other inputsKeep records of application rate and timingof other inputs such as; insecticides, irrigationetc.Crop monitoring recordsYour crop should be regularly checked<strong>for</strong>; weed, pest and disease pressure,establishment and harvest maturity. Thoseirrigating may monitor soil moisture andrainfall. Keep records of all crop, soil andweather monitoring.HarvestRecord the harvest date(s). If you are notweighing your crop, ask your technicaladvisor and/or contractor <strong>for</strong> their bestestimate of crop yield and DM%. Oncompletion stacks can be easily sampled<strong>for</strong> analysis of DM% or feed quality. Thisis done regularly <strong>for</strong> traded maize (chapternine) your harvesting contractor should beable to arrange this.21

11. Resources and furtherin<strong>for</strong>mationDairyNZwww.dairynz.co.nzPh 0800 4 DAIRYNZ (0800 4324 7969)Resources Available include:Feed in<strong>for</strong>mation Sheet - contains all thefeed supply and demand numbers required<strong>for</strong> daily and annual feed requirements ofdairy cattleFeedPlan Pro - is designed <strong>for</strong> farmersand consultants wanting a simple, quickand visual way of feed budgeting andmonitoring.Environment Waikatowww.environmentwaikato.govt.nzPh 0800 800 401Resources Available include:Fact sheets and brochures on nutrient, soiland effluent management, website providesin<strong>for</strong>mation on; best management practices,tools, environmental monitoring dataas well as various technical reports. Staffare able to provide farm specific guidanceand advice related to land managementand waterway protection. Workshops andField days on best management practice.Pioneer Brand Productswww.pioneer.co.nzPh 0800 PIONEER (0800 746 633)Resources Available include:Pioneer <strong>Maize</strong> Harvest Guide 2006, BunkerCalculator, Silage harvest and stack buildingPioneer Technical Insights 302-304 foundat www.pioneer.co.nzOther resources include:NZ Weeds in colour - NZ Plant ProtectionSocietyLand <strong>Management</strong> to Grain <strong>Maize</strong> - Crop &Food Report 361 - Plant & Food ResearchSeed, Rural Supply and Fertiliser CompanyBookletsContractors, Consultants, Seed and RuralSupply repsFoundation <strong>for</strong> Arable Researchwww.far.org.nzPh 03 325 6353Resources Available include:AmaizeN Fertiliser Forecaster, <strong>Maize</strong>Action Newsletter, Arable Updates, Costof Production Worksheet, <strong>Maize</strong> ForageTrading Code of Practice, Field days andWorkshops, Grass Weed <strong>Management</strong> -the Ute Guide22

12. Glossary$BW BW - Breeding Worth. The unit is $.The genetic index given to cows and bulls <strong>for</strong> their ability to turn feed intoprofit.BW ranks bulls and cows on their expected ability to breed replacementswhich will be efficient converters of feed into farmer profit. It is used as aguide to making breeding decisions. Breeding Worth estimates are comparableacross herds, ages and breeds.An estimated Breeding Worth of +$100 indicates that using this animal asa parent of a replacement is expected to generate an extra $100 profit peryear per 4.5 tonnes of dry matter consumed, compared to using a parentwith a BW of zero.DMCRMGDDKKLWGMEMSNPTDry matter.Comparative relative maturity, a rating of the maize maturity. High valuesindicate that the crop will take longer to mature.<strong>Growing</strong> degree days, a term used to describe the accumulated days whenthe average temperature is over a certain base temperature. For maize,GDD’s are calculated using a base temperature of 8 o C.GDD = (max + min temp) - 82Potassium, when referring to nutrients.One thousand, when referring to plant population. 89 000 plants per hectarecan be describe as 89K/ha.Liveweight gain.Metabolisable energy, a measure of feed value. Reported as megajoulesper kilogram of dry matter (MJ/kg DM).Milksolid.Nitrogen.Phosphorus.Tonnes (1000 kg).23

Notes24

“<strong>Maize</strong> is a vital crop <strong>for</strong> many New Zealand dairy farmers; it alsorepresents a significant investment in time and resources. Thisbooklet aims to give farmers the tools that they need to extractmaximum value from this investment, providing the most topicalin<strong>for</strong>mation on maize crop preparation, management and harvest, inone easy to access resource.”This technical guide is brought to you from: