Category: Soil & crop

Less soil compaction on grassland 

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Soil compaction is one of the biggest problems facing agriculture today. The main causes of compaction are heavy farm machinery, intensive cultivation, limited crop rotation, intensive grazing and poor soil management. Compaction is aggravated by a low organic matter content and working the land in wet conditions. Here are some tips to avoid soil compaction.  

What is soil compaction? The pores that naturally occur in soil are used for the exchange and transport of water and oxygen through the soil. This function is vital for the root zone of plants. Soil compaction reduces the volume of the pores so less water and fewer nutrients can be stored in the soil. This negatively impacts on grass growth. There is strong correlation between soil compaction and reduced grass growth and yield. 

Soil compaction is difficult to rectify  

Soil compaction is a difficult problem to rectify, so prevention is better than cure. Deep tillage to de-compact the soil is often needed to mitigate the effects, but this affects the natural soil structure. So, it’s best to prevent compaction rather than solve the problems it causes afterwards. 

This can be done by always working the land in dry conditions. As this is not always possible, it is important to carefully consider which machinery you will be using. Limiting the number of passes and combining work passes – e.g. baling and wrapping – reduces the risk of soil compaction. Transferring newly wrapped bales as much as possible from the wrapping table to the headland limits field traffic when the bales are collected as less movement of heavy machinery – such as bale wagons, telehandlers or loaders – is necessary over the field. 

Preventing soil compaction

To limit the impact of traffic on the soil, it is important to minimise the weight of the combination and, where possible, reduce the tyre pressure. A light machine combined with a trailed implement suitable for the task is the ideal scenario. The basic principle is the lowest possible combined weight.  

The tyre pressure of lightweight combinations can be reduced further once in the field. Consult the pressure table of the tyre manufacturer. Opting for an additional wheel axle allows the tyre pressure to be lowered further. With optimum tyre pressure – preferably below 1 bar – the pressure exerted per cm2 on the soil does not increase when the bale chamber fills with grass or when a bale is on the wrapping table. As the weight increases, the tyre will flatten and therefore distribute the weight over a larger surface. This minimise damage to the grassland. 

The ideal cutting height for the best regrowth

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Harvesting each cut as cleanly as possible from the field, followed by optimal regrowth. The essence of cutting is determining the cutting height. The following applies: cutting slightly higher than needed ensures a cleaner cut of grass and encourages quick regrowth. 

As a rule, cutting the grass to around 5 centimetres above soil level is advised. “But applying that cutting height as standard is not always the best strategy,” says Sjon de Leeuw, Advisor Management and Strategy at the renowned Dutch consultancy PPP Agro Advies1. “Several factors influence how you determine the correct cutting height: the age of the grassland plays a role; and another determining factor is the moment of harvest. It’s important all year round to avoid cutting the growing point of the grass as this seriously affects the chances of good, rapid regrowth.”  

Cutting height and harvesting moment 

In spring the growing point of the grass is slightly closer to the soil level than the level in mid-summer. It then becomes closer to the soil again in autumn. “That explains why you can’t cut your grass at the same height all year round,” says de Leeuw. “The growing point changes during the season and if you are harvesting from grassland that is a little older, then the cutting level may need to be higher – whatever the situation, it is important to adapt your cutting height during the season.” When harvesting grass for silage, don’t just concentrate on the grass you are cutting now, but think about the next cut. “Cutting higher may reduce the yield slightly, but you will quickly recover that loss within a week thanks to good regrowth. And that gives you benefits in the second cut,” explains de Leeuw. “Assuming you can harvest five cuts in a season, and they are cut at the right height each time, good regrowth means you can realise about two weeks of extra growth days.”   

Minimal amount of crude ash in the grass

Once the correct cutting height has been determined, make sure all machines are correctly adjusted accordingly. “You can set the cutting height to 7 centimetres, but if the tedder, rake and pick-up of the silage chopper or loader wagon are not adjusted to that height, there is still a risk of crude ash in the grass. Adjust the machines accurately and always do a final check in the field. Drive a short distance, then get out and check the adjustment heights. Too high settings are not necessary but do make sure all the separate pieces of equipment are correctly aligned mutually for the best results.” 

 

Preparing grassland for the new season

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Every farmer wants to get the best possible yield and the highest possible nutritional value in the bales with the first cut of grass. Proper preparation in the months before the first cut ensures an optimal start of the grass season. 

In spring, the first treatment that needs to be done on grassland is flattening any molehills. In addition, it is advisable to lightly roll the grass that is just starting to grow, with the emphasis here being on ‘lightly’, because the grass haulm is still very sensitive at this time of year. Soil that has been compacted too firmly heats up less quickly in spring, which reduces the rate of grass growth. Any aggressive tillage in spring is strongly advised against.  So, leave the heavy-duty roller in the shed, as well as the harrow with sharply adjusted tines. Just as gentle operation with the harrow or a chain harrow is enough.  

Under-seeding in autumn or spring?

Under-seeding in spring is only necessary if the grassland has suffered heavily in winter or has been damaged by wildlife. In that case, there will be hollows or bare patches in spring. It is advisable to under-seed as early as possible, as soon as the bearing capacity of the soil permits.1 If there are no hollows or bare patches in the grass do not overseed. The existing grassland is too much competition for the young germinating grass. The best time to under-seed established grassland is autumn, as the soil temperature is higher than in spring. It is also best to wait for a good moisture content in the soil.   

No chain harrow? Then use a tine harrow.  

If a drag harrow is not used in spring, the right alternative is a tine harrow with the tines adjusted as diagonally as possible to avoid any aggressive tillage. This will treat the grass as gently as possible. The purpose of using a tine harrow is to loosen and level the surface very slightly without aggressively working and disturbing the soil.

Caring for your grass with a meadow aerator 

If there are issues with the structure of the grassland, aerating is a good option. Problems include compaction caused by heavy machines or intensive grazing. Renewing the grassland is also one of the options, but this comes at a cost. To encourage and restore good rooting of the grass and ensure good uptake and utilisation of minerals, aerating in spring is recommended. At this time, the grass roots can penetrate and grow directly into the spaces created by the aerator3. Aerating is becoming an increasingly common place component of good grassland management. It is an interesting practice because it involves a limited investment by the farmer or contractor and it can be done as soon as necessary.  

Fertilise as soon as possible 

Applying slurry early results in a higher yield of dry matter than applying late, even if a higher quantity of manure was applied at the later date4.  It is advisable to start fertilising as soon as the bearing capacity of the soil allows. Apply around 10 to 20 cubic metres of cattle slurry per hectare. If artificial fertiliser is used, the highest nitrogen utilisation and yield in the first cut is obtained with a nitrate fertiliser (e.g. CAN)5. This should be applied at a T-sum of around 300. (The ‘T-Sum’ value is the accumulated mean daily temperatures (in ° C) above zero, starting on January 1). The highest yield and utilisation of slurry is obtained if it is applied as soon as possible, provided soil conditions permit. 

Home-grown protein, make sure you feel the benefits!

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The proportion of home-grown protein. In other words: the quantity of home-grown protein divided by the quantity of protein in the ration. Managing forage production effectively offers plenty of benefits to dairy farmers. “Poor management of the entire process, from producing the best first cut of silage grass to presenting the forage at the feed fence, can make a negative difference of around €7 euros per bale. Harvesting quickly and cleanly, then preservation in airtight conditions is vital,” says Sjon de Leeuw, management and strategy advisor at PPP Agro Advies.

A dairy farmer’s business model all depends on its farm management. De Leeuw: “Feed rations account for the biggest expense on a farm. Farmers feel the financial implications of buying minerals, concentrates and other ingredients. But one area they do have some control over is the production of protein.”

As much as possible from your own land

It is important to aim for the maximum protein yield from your own land, as this logically reduces the dependence on protein from external sources. Quantity and quality are both equally important here, as well as maintaining the right energy to protein balance in the ration. Too much protein can have a detrimental effect on the animals, so every farm aims for the optimum protein content in the bales or silage.

Influential factors on protein

“In practice, I regularly see wide variations in how much home-grown protein is produced on farms. In some cases, one farmer harvests less than 50 per cent protein from their own land while another farmer gets more than 65 per cent – even though the number of cows and hectares of grassland are the same. This suggests that farmers who produce more protein on their own land manage forage production and feeding far better,” says De Leeuw. According to the advisor, contributing factors include the harvesting method, the time of harvesting and the way of preserving. To ensure good preservation, the speed of harvesting and getting the grass wrapped airtight as quickly as possible are essential.

De Leeuw: “And bear in mind that the optimum dry matter content is around 40 per cent. You can work with percentages of 50 or higher, but that increases the risk of heating. But what makes this complicated is that the protein in drier grass is generally more rumen-resistant, i.e., of better quality. But the friction between drier grass increases the risk of heating.” One of the causes of heating is a higher dry matter content combined with inadequately sealed material. This effect can be amplified by a low face removal rate of the silage. The lower the removal rate, the longer the period that oxygen can enter the silage mass. And if oxygen is given free rein, heating will inevitably occur. Feeding bales uses up the forage faster, so the risk of heating in the bale is considerably lower than in silage.

Different bales for optimal rationing

The protein content of grass harvested in summer is often lower than in grass baled in autumn. The differences affect the ration and how the cow utilises that ration. De Leeuw: “To get an optimal percentage of protein from their own forage, it is important to mark the bales obtained from different harvests and have them analysed. This information means you know what you have and where it is stored. To keep the protein content at the same level, various bales can be mixed to create the ration. Autumn grass is best suited for dairy cattle. Provided it has been harvested properly, it is palatable and combined with a bale with an appropriately low protein content. A low-protein bale on its own is more versatile and can also be fed to pregnant or dry cows at any time.”