Frost Damage

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FROST DAMAGE and what to do next

THE RECENT COLD SNAP BROUGHT FROST TO SOME MAIZE FIELDS. IF YOU’VE NOT SEEN IT BEFORE OR ARE WORRIED WHAT IT MEANS FOR YOU – HERE’S A SHORT NOTE TO HELP UNDERSTAND.

What is frost damage?

Frost damage occurs when temperatures drop below freezing, causing ice crystals to form within plant cells. This can lead to cell death and tissue damage, particularly in sensitive parts like leaves.

Why is frost damage a concern for biogas plants?

When frost damages maize plants, it can negatively affect the biogas yield and quality:
Reduced Sugar Content: Frost can scorch leaves, leading to a loss of valuable sugars. Sugars are essential for the fermentation process that produces biogas.
Increased Clamp Spoilage: Damaged plants are more susceptible to spoilage due to increased microbial activity. They can also be harder to compact and ensile. This can reduce the overall quality of the feedstock and as a result the quantity of biogas they will yield.

Minimising the impact of frost damage

In the event you get a snap frost and the crop takes on the look of that in the photo herein, it’s not all doom and gloom:

Inspect: check to see if leaves have been damaged to the cob. If there are still green stems and leaves, the plant will continue to produce starches and can be left to mature. Go beyond the field edges – as early frosts are often light, plants several rows in are sometimes insulated and ok.
Timely Harvest: Harvest within 48 hours of a frost event. This will save some of the sugars and can help minimise further damage and preserve the crop’s nutritional value.
Proper Preservation: Chopping the crop short (aids compaction) and using additives can help prevent spoilage and maintain the nutritional value of the maize in the clamp.

Asking an expert like FORAGER FEEDS (with qualified agronomists working exclusively with crops into biogas plants) can provide valuable guidance if you need help deciding whether to harvest your frost-damaged maize or how to handle it properly. FORAGER can help assess the situation and recommend the best action for your specific circumstances.

IF YOU COULD DO WITH ADVICE ON CROP QUALITY, GROWTH STAGE, HARVEST or CLAMPING – WE CAN HELP

IS YOUR MAIZE READY?

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IS YOUR MAIZE READY FOR FORAGING?

We’re often called by biogas operators to advise on whether a crop is fit and ready to go.

Maize is a staple of biogas plants and a good or bad year can have a huge influence on the whole feedstock supply chain – so getting it right (or as right as you can) is important. At this time of year maize DM is increasing by 0.3 to 0.5% per day. Too early and you may have a wet crop – too late and those all important sugars and starches are turning to brown lignins and compaction is more difficult to achieve.

Add to the equation weather. A heavy downpour can make field clamps/ ag-bagging areas inaccessible, damage soil and fields and cause public nuisance carrying soil onto the highways. So knowing “when to go” in the midst of foraging weather-windows, while balancing supplier/ customer interests is important.

There are two quick tests:

The twist test – shown in the video here – when the stem is twisted at the lower node, free water should not leach from the stem as in the video. This maize is between 25-26% DM by our estimate and if harvested would release a lot of liquid in the clamp and may even turn to “mush” in places. For a biogas plant this could represent a 25-40% reduction in value in the digester (when losses and reduced gas production are accounted for.
The squeeze test – video to follow – but when a single kernel is squeezed, there should be resistence and a hardness to it. If it is soft and “pops” (if you’re eating look away now) like a zit, then it is not fit and not ready for foraging.

IF YOU COULD DO WITH ADVICE ON CROP QUALITY, GROWTH STAGE, HARVEST or CLAMPING – WE CAN HELP

Planning your maize harvest

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Planning your maize harvest yet?
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Hands-on dm assessment can give a quick guide as to where crops are

Sidewall sheeting and creating thin layers for compaction will help make good quality silage

Maize drilling may not yet seem a distant memory… but with the recent warmer weather, we should be looking towards maize harvest.

Assessment of dry matter

Predicting the likely harvest date of your maize crop is an essential part of harvest preparation. The recent warm weather means that the maize crop continues to push through its growth stages. Assessing the dry matter of your maize and using dry down rates will help you predict the potential harvest date of your crop.

You should aim for the dry matter of your crop to be within the target range at the point of harvest. The target dry matter percentage for maize is between 30-35%. This applies to livestock maize and maize for biogas, although biogas plants usually expect a wider range (30-38%) to reflect a more extended harvest campaign.

When commencing harvest, it is advisable to follow varietal maturity and start chopping with the fastest-maturing varieties. You should also aim to complete harvest before varieties reach 38% or more dry matter, this will help maintain the quality of silage.

Methods for assessing Dry Matter

There are several different ways that you can measure your maize dry matter:

The Milk Line Test:

The ‘in-field’ test is known as the ‘Milk Line Test’. This test looks only at the grain and then judges the overall DM of the plant based on the line where the ‘milk’ meets the starch. See the guide in the pictures to the left.

The Milk Line test method involves taking a randomly selected representative cob and snapping it in half. Within a field there will be natural variation in the cob; getting a representative cob is essential for this test. Remove a kernel from the cob and run your fingernail along the length of the kernel, starting at the flat/dented end and working towards the end that was attached to the cob. Note the point where the solid starch ends, and the liquid milk begins. To hit target DM, you are aiming for the milk line to be ⅓ to ½ way down.

Oven-based Testing:

Whole plant dry matter testing can be done in a microwave, oven or, as researched by the MGA, in an air fryer. The following calculation can be used to work out the DM% of your sample:

Dry (post oven) weight (g) ÷ Original fresh weight (g) × 100 = Dry Matter percentage (DM%)

Microwave oven – Dry the sample in the microwave for ten minutes and then pause to stir. Dry for another ten minutes and then stir again. After this, dry for only five minutes and weigh the sample. Record this weight and then return the sample to the microwave for a minute or two at a time, weighing at each interval. When you get two consecutive weights the same, your sample is dry. Record this weight as the final dry weight and perform the calculation above. Keep a close eye on the maize through this process. If it dries out too much, it may smoulder and catch alight! You can put a glass of water in the microwave alongside the sample to reduce the risk of over-drying.

Oven – Dry in an oven for 16 hours at 105°C. Weigh the product again and record the dry weight. This is a very reliable and accurate method of assessing the dry matter. However, it is time-consuming and will not give you a quick result.

Air fryer – This is the preferred method of oven-drying a sample at the MGA as it is less volatile than the microwave method but is much quicker than the full oven procedure. For a small sample, we have found it possible to dry at 110°C for only 40 minutes, but 90 minutes would be appropriate if the air fryer is fuller. As with the microwave method, if you are unsure of timings, weigh the sample and then dry for another few minutes and weigh again. If the weight remains the same, it is fully dry.

Chop quality

Maize for livestock is chopped to around 12mm, with a longer chop of about 18 – 22mm used in some circumstances. Individual choice of chop length will depend on how the maize is being used. Maize for biogas tends to be chopped more finely at 5-8mm as this allows a greater surface area for the microbes to work on.

Grain processing

Making sure the kernels are broken is an important quality parameter. This ensures maximum energy output from the maize and that the kernels do not become undigested. The kernel processing unit in the forager should be set up depending on the maturity of the grain. When maize crops reach a higher degree of maturity with large, hard kernels, it is essential that processing is done adequately. If the kernels are hard, they must be well crushed or broken into 3-4 pieces.

Additive

Maize ferments well and does not typically require an additive to establish a stable fermentation. After an assessment, additives may be added to give better aerobic stability and keep the quality of the silage, to improve digestibility, intake and feeding value.

Clamping

Maize silage needs to be made quickly, well consolidated, and completely sealed to allow anaerobic fermentation to occur. Ideally, the weight on the clamp should be at least 25% of the hourly fill rate, i.e. 100t/hr fill rate requires 25t of machines on the clamp. Fill the clamp in thin layers using a shallow wedge. To ensure that the whole clamp, including the shoulders, is well compacted, consolidate thoroughly from the bottom, and fill and roll the clamp continually.

Sheeting

Good sealing of the clamp is vital. Side sheets, as well as an oxygen barrier sheet, should be used. This layer is thin enough to be sucked onto the maize surface as oxygen is used up but tough enough to remain intact when laid out. Weigh down the top with plenty of gravel bags. Continue to monitor the clamp throughout the year and repair or replace sheets if they become damaged to minimise aerobic spoilage.

IF YOU COULD DO WITH ADVICE ON CROP QUALITY, GROWTH STAGE, HARVEST or CLAMPING – WE CAN HELP

What’s happening with Maize?

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What’s happening with the Maize?
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Maize Crop 2024: A Story of Variability, Delays, and Tightening Stocks

The 2024 maize harvest is shaping up to be one of stark contrasts, with crop conditions varying significantly across the country. Delayed planting due to a wet spring, followed by unseasonal weather fluctuations, has resulted in uneven development and pushed back planned harvest timelines in many regions. This variability has significant implications for feed supplies, particularly as stocks of 2023 maize dwindle.

Varied Growing Conditions Across the Country

While some areas benefited from well-timed rainfall and moderate temperatures, others experienced prolonged wet and cold spells. This has led to a wide range of crop maturity levels, with some fields over shoulder height in early July, which look set for a normal harvest timing while others lag considerably behind. This unevenness poses challenges for farmers and contractors alike, who must navigate disparate harvest windows and manage the logistics of harvesting and clamp crops in varying dry matters and quality.

Harvest Delays and Stock Concerns

The delayed harvest timeline is raising concerns about the availability of maize for feed, especially as existing stocks from 2023 are rapidly depleting. September, typically a month of transition between old and new crop maize, will likely increase supply pressure. The shortage could be particularly acute for those who rely on early harvested maize varieties, which may be in shorter supply due to weather-related setbacks.

Planning for Shortfalls: A Proactive Approach

Given the anticipated stock tightness, biogas producers must assess their feed requirements and plan accordingly. Identifying potential shortfalls in maize supply early on allows for proactive measures, such as securing alternative forage sources or adjusting feed rations. This proactive approach can help mitigate the impact of tight maize supplies on the fermenter’s health and productivity.

Forager Feeds: Your Partner in Forage Solutions

In these challenging times, Forager Feeds is well-equipped to assist biogas producers in navigating the maize market. With a wide range of forage products and expert advice, we can help you identify suitable alternatives to maize, develop tailored feed solutions, and ensure your plant’s needs are met.

Whether you require additional forage supplies to bridge the gap during the harvest delay or seek long-term security in feedstocks, Forager Feeds is your trusted partner in forage solutions.

image to the left shows purple leaf caused by poor phosphate uptake as a result of cold soil temperatures during the early growing phase

“Maize may be increasingly marginalised by a drive to reduce reliance on purpose grown crops – however, it is still the baseline feed underpinning the market, the impact from which sends ripples through everything else. In short, if maize sneezes, the biogas industry catches a cold.“

Why use high performance feedstock?

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Why use high performance feedstocks?

There are a number of high cost, high performance feeds available in the UK for biogas plants – but in general, they’re “very expensive”. So why pay £100-250 per tonne for a high performance feedstock? There are two fundamental reasons to take the plunge – performance and the risk/ reward.

Performance

The headline is that they produce a lot of gas, usually very quickly and usually with a high methane content. Quick means more space in your digester for other things and high methane means more energy (more revenue) per unit of biogas produced.

Quick can be good (carefully managed) because getting your gas out in fewer days means you can process a higher throughput (annual capacity) – meaning your energy output from the same sized plant is higher. Or you can produce the same amount of gas from fewer tonnes – so things like shutdowns/ feed blockages can be more easily caught up.

High methane is great as you’ll make more kwh from the same gas in your CHP or your upgrader can make more smch of methane from the limited modular volume throughput.

But most importantly are the multitude of small benefits not immediately seen, felt or noticed – they don’t turn up in the revenue line but make subtle impacts on your costs. Lower power consumption, reduced wear & maintenance costs, longer maintenance intervals, reduced fuels and other consumables – even improved operator morale.

Risk Vs Reward

Generally though, they’re less profitable. That is, assuming your best optimistic performance plans are realised. The key here is predictability. Generally these “high performance” feeds are highly predictable. Consistent delivery, consistent gas yield, consistent quality, consistent consistency. Something that higher reward feedstocks (like post consumer commercial food, depacked blends or household wastes) lack. A safe pound versus a risky two pounds if you like. If you factor in a more pessimistic view of blockages, damage, wear, production inefficiency and other impacts/ inhibitions from variable/ contaminated feeds, then things even up somewhat.

In truth, a sensible balance can be struck. Spreading of risk (whereby a baseline of known consistent feeds gives comfort, with riskier, ad hoc and high performance feeds making up the balance) allows the plant to hedge their position without fully benefiting from or exposing itself to the risk of either.

In truth, this is a snapshot and generalisation of the market – a silhouette on which to paint the detail.

If this is of interest, please contact us to further discuss how Forager Feeds can help you map out the best balance of feeds to suit your operation needs and risk appetite.

Forager Feeds is a specialist biogas feedstock manager, supplier, consultant, project manager and agronomist. Our people have been working with feedstock in biogas for over a decade and have an innate understanding of “how it works”. Our goal is to make sure you get the best out of your feedstock.