Case Studies - Facts of Lime

Product Sector: Agriculture

Industry: Agriculture - Dairy and Dry Stock

Products: Aglime

Interviewees: Paddy Shannon M.Agr.s (Hons) MNZIAS - Farming Consultant

Location: Te Awamutu
 

Application of nitrogen will acidify a soil.

Without countering nitrogen induced acidity it is likely farmers will end up with poor responses to applied fertiliser as plants are less productive in acid soils.

How much Lime?

This graph shows the amount of lime required to neutralise the acidity released by different types on N on an applied basis.

Different forms of nitrogen have different levels of lime demand.

• Applying nitrogen (N) fertiliser makes the soil more acidic. The change from ammonium or urea to nitrate leaves the hydrogen behind to acidify the soil. The amount of acidity depends on whether the applied N is leached as nitrate or taken up by plants and exported in produce.
• The degree to which this occurs will vary depending on soil conditions and the form of N applied.
• An average dairy farm applies around 90kg N/ha/year, but this can range from 0 to 150kg N/ha/year. Most nitrogen is applied as urea so at 90kg/N/ha/year the derived lime requirement is 160kg of pure lime, or 180kg/ha of Aglime (90% purity).
• Farms at the high end of N applications are therefore likely to need 290-300kg of aglime to correct the N-induced acidity.
• Di-Ammonium Phosphate (DAP) is usually applied as an effective way of getting a strategic seasonal N dressing on by teaming it with the autumn or spring P-fertiliser application. Given that a typical dairy farm will need around 35 to 40kg P/ha/year, the N applied in this way as part of the program will total 31 to 35kg N/ha-which equates to an aglime need of 125 to 160kg lime/ha/year.
• Mono Ammonium Phosphate (MAP) and Sulphate of Ammonia (SOA) being ammonium-based fertilizers will always acidify the soil. A tonne of MAP needs 580kg lime per tonne applied, while SOA needs 1100kg per tonne applied, as shown in previous graph.
  
  

Why Nitrogen Needs Lime

• Applying nitrogen (N) fertiliser results in the soil becoming more acidic. The degree or extent of acidification is determined by whether the applied N is leached as nitrate, or taken up by plants and exported in produce.
• We can look at the extremes – all taken up, or all leached as nitrate. For urea, the two extremes are no acidity, or acidity requiring 3.5 kg of lime per kg of N applied to neutralise it. As we can’t reliably predict which is going to happen, we plan on the average: around 1.8 kg lime per kg of N added or, for every tonne of urea containing 460 kg of N, you will need 830 kg of lime.
• Unlike urea, ammonium fertilisers will acidify even if all applied N is taken up. The lime requirement ranges between 3.5 and 7.0 kg (average 5.3/kg) of lime for every kg of N applied. Sulphate of ammonia with 210 kg N per tonne, or MAP with 200 kg of N per tonne, both need around 1.1 tonnes of lime per tonne applied.
• DAP sits between sulphate of ammonia/MAP and urea needing an average of 3.6 kg lime per kg of N applied, because the P it contains uses up some soil acidity when it is absorbed by plant roots. With 180 kg N tonne, 650 kg of lime are needed per tonne of DAP applied. When planning N applications, you need to allow for the acidity created. This becomes more important if you use relatively large amounts of N. Without countering nitrogen-induced acidity, it is likely that you will end up with poor responses to N fertiliser, as plants are less productive in acid soils. Put another way, keeping your soils well limed with pH levels around 6.2 will guarantee the best possible response to nitrogen fertilisers whenever you need to use them.
  
  

Light Rate Annual Liming

Light rate annual liming is the best way to counter nitrogen induced acidity. Farms following this practise have seen some great results. They are also gaining all other benefits of maintaining a soil pH around 6.2, such as;

• Improved soil structure and better nutrient recycling through greater microbial activity,
• Greater drought resistance through increased root depth and soil moisture retention capacity,
• Improved pasture palatability,
• Increased clover content and overall better pasture composition giving higher total pasture ME.
  
  

Thoughts of the Farmers

• “The paddocks that have been limed are a mass of clover and beautiful green grass. When we first came here the cows would pull the grass out of the ground as it was all just sitting on top. Now when I’m fencing, I see a lot of worms and the roots will be 200-250mm deep. In the last 4 years my baleage harvest has increased each year. The first year we got 56 bales out of three flat paddocks. This year we’re up to 72.” – Wayne Cederman, Otorohanga
• “We have seen a marked turnaround in our farm since starting an annual liming programme three years ago. The regular application of lime has part in improving soil condition and pasture palatability. Since we started an annual liming regime, the farm is slower to dry out and quicker to respond when rain comes. We put on lime each spring and it has saved us a lot of money in fertiliser” – Ron Hamilton, Otorohanga

Product Sector: Agriculture - Dry Stock

Products: Aglime

Source: Farm Production and Practice-Ministry of Agriculture and Fisheries (AgLink) 

• Low soil fertility is still a major factor restricting production on North Island hill country. Many properties still have a low phosphorus status and low soil pH.
• Although information is available on the phosphorus requirements of many of our hill soils, less is known about lime. This AgLink presents findings of preliminary research on lime, and discusses its value on hill country.
• The research is being carried out at Te Kuiti on Mahoenui steep land soils (Mudstone soil), with a pH of 5.5. This soil is typical of approximately 400 00 ha of North Island hill country. Research investigated the production responses to low application rate of lime (1.25 t/ha).

Ewe live weight and pasture availability

The main research features are:

• Lime increased pasture production.
• The main response appeared 15 months after application
• The response to lime continued and increased over time and was still present 3 years after application.
• The delayed response to lime is probably due to a combination of two factors: the low rate of application and low solubility of the limestone.
• Even with a high rate of lime (5t/ha), it can take up to a year for ground limestone to have its maximum effect on soil pH and Calcium levels.

Wool production

• Fleece weights of both ewes and lambs show a response to lime. Additional 0.5-0.6 kg greasy wool per ewe and up to 0.13kg per lamb was obtained-due to the better overall plane of nutrition of the animals grazed on limed pasture.
• The effect of lime on wool characteristics, in particular fibre diameter, confirms the benefits of an improved nutritional regime.

Lamb performance

• No valid comparisons can be made between lime and no lime treatments on lambing percentage, because of low ewe numbers.
• The lambs from pastures receiving lime were, however, superior in live weight at weaning. ‘Lime’ lambs were on average 3kg heavier, mainly due to a better level of feeding.

Reasons for improved stock performance with AgLime

• AgLime increases animal production through an increase in pasture production.
• In addition there is some evidence to suggest lime also improves the legume component and decreases the amount of pasture litter. Earthworm numbers on the lime treated land also tended to increase.

Conclusion

• A low rate of lime on a steep hill country soil increases pasture and animal production.
• There is no response for 15 months, but thereafter lime increases ewe live weights by approximately 5kg/ewe, ewe fleece weight by 0.5-0.6 kg/ewe and lamb live weight at weaning by at least 6%.
• The response appears to be due to an increased total pasture production rather than any improvement in pasture quality.
• An economic appraisal of the results suggests lime usage is very profitable.

Case Study: Lime and Farming

Product Sector: Agriculture-Dairy

Location: New Zealand

Products: Ag Lime, Calcimate and RaceFines

Source / Interviewee: Dave Muggeridge

Introducing Dave Muggeridge

• Dave Muggeridge milks 280 cows on his 90-hectare farm in Tatuanui, in the Waikato.
• He is one of 112 shareholder farmers who supply to the local Tatua Cooperative Dairy Company.
• Dave employs a contract milker, leaving him to focus on the management of the pasture and stock.

The challenge: optimising farm production through growing more grass

• Dave is passionate about boosting productivity through better pasture management.
• “In this country we don’t grow enough grass to fulfil the potential of the New Zealand cow,” he says. “We don’t need to put more cows on – we just need to grow more grass!”
• Dave uses three lime products on his farm – for pasture, Calcimate® for a feed supplement, and RaceFines™ for the tanker track.

“I use AgLime and 2-6 Chip to alter the pH, increase the microbial activity in the soil and hence improve soil structure. The lime makes the grass highly palatable. So while it doesn’t change the number of mouthfuls a cow is eating each day, it does mean there is more in each mouthful. It makes the grass thicker (a bit like a NZ Wool carpet!) and highly nutritious.”

Why McDonald’s?

Proven history

• At his previous property, Dave used to apply lime to a quarter of the farm each year – and observed that it was the best-performing pasture.
• “From this, we decided to apply Ag Lime at a lighter rate over the whole farm. Now we lime the whole farm every year.”

Profitability

• In a nutshell, the lime helps grow more grass – which is the cheapest form of dry matter, especially compared to supplements such as maize or palm kernel.
• “You’re not writing out cheques for silage and you don’t need extras like a feed out wagon,” explains Dave. “Using a grass based system helps improve margins, and that’s especially valuable in low-margin periods.”

Better for the environment

“We’re growing a lot of grass and not leaving a footprint. And we’re not having a lot of nitrogen escaping out of the system.”

Quality product

“We have very active soil and lime is an integral part of soil fertility. McDonald’s (now Graymont's) is the best quality lime available.”

Results

To sum up, Ag Lime has provided measurable improvements in pasture production; Calcimate® prevents Dave’s cows from becoming hypocalcaemic after calving; and the RaceFines™“compacts nicely, just like the road”.

“We’ve been working with McDonald’s (now Graymont) since 1996,” says Dave. “The cows are satisfied and the results are very encouraging. There’s always grass, even in a drought period.”

Product Sector: Agriculture - Cropping

Product: AgLime

Source: Paddy Shannon, M.Ag.Sc.(Hons). 

Low pH = low yield. Correcting low pH conditions can lead to large yield increases – often in the order of 20 to 50%. Preparing for this summers’ maize and fodder crops means starting to plan now.

Preparation

• An important part of the process is to make sure that the soil in the cropping paddocks is set up to give you the best possible yield that the climate will allow.
• Good preparation can help to offset the effects of cooler or drier than optimum conditions.
• A vital and often overlooked part of your preparation is to make sure that soil pH levels are where they ought to be.
• If you are taking the worst performing paddock and using the cropping process to prepare it to support high-yielding pasture after the crop, then you should realise the crop needs good soil conditions as well.
• Plan to have the soil in good order before you sow the crop. This way you can “write off” the costs of soil improvement for the new pasture against the cropping process - $500/ha spent on fertiliser and additional lime against a 20-tonne maize crop represents 2.5c/kg DM.

What you should be looking for?

Maize Crops

• Maize has to have a soil pH over 5.5 (using a 15cm deep sample).
• Many guides suggest a pH of 6.0 should be used because the crop will tend to acidify the soil when it takes up nutrients as it grows.
• Most maize is not fed out on the paddock it is grown in, so the acidity will remain. If pH levels are low, liming to above the minimum level can give yield increases of over 15%.
• Also, if you get pH above 6.0, you will only need to apply maintenance lime to your pastures.

Summer Brassicas

• For summer brassica crops such as turnips (leaf or bulb), rape and kale, the target pH is 6.0.
• With proper soil fertility management (including nitrogen use) these summer crops can easily yield over 10 tonnes of DM/ha, so an expenditure of $500/ha on soil fertility comes to only 5c/kg DM.
• If you leave out liming and only spend $450/ha but lose 30% of the yield, the soil fertility cost rises to 6.4cents/kg DM.
  
  

What should you be doing now?

• Identify the areas you are going to put into crop.
• Soil test them all – even areas doing a second round, because high yielding crops can make big demands on soil resources and pH can change even after one such crop – using a 15cm probe.
• Once you have the results, work with your contractor and consultant to identify the soil fertility needs.
• If lime is required, make sure that it goes on early in the crop preparation process so that by the time your new crops are getting established, they are in soil that is in the best possible condition to give you the optimum yield.

Case Study: Lime and Farming

Product Sector: Agriculture-Dairy

Location: New Zealand

Products: AgLime

Source / Interviewee: Mike Earwaker

Case Study: Lime and Farming

Product Sector: Agriculture-Dairy

Location: New Zealand

Products: AgLime

Source / Interviewee: Hugh Chisholm