Pioneer: Silage: Cutting window forecast

Maize silage is the most important part of a balanced feedlot or dairy ration. The starch in maize silage is the energy source of the ration, and also the cheapest form of starch.

Some of the most important factors for good quality silage are:

• cutting at the right moisture percentage, in other words, the dry matter value;
• bunker compaction; and
• the time from cutting to closing the silage bunker, in other words, the exclusion of oxygen.
• However, the most important factor is the right time for cutting and making silage.

Pioneer Seed has been investigating the use of a silage model to predict cutting time for South African silage producers for the past 3 years.

To better understand the picture, it is necessary to take a step back and first look at the background of cutting time.

Milk line

To determine when it is the right time to cut maize, it is necessary to determine where the milk line is on the head. This remains the easiest, from-the-loadbed-of-the-bakkie way to determine cutting time. The ideal is to cut from the 50% milk line. At 50% milk line, the dry matter (DM – value) should be 35% DM.

Figure 1. Difference between the optimal and non-optimal cutting window.

What are the disadvantages of determining the milk line?

• Pivot points are usually homogeneous and easy, but dry fields are not so simple.
• Physical field inspections should be done every 5 days from day 95, and closer to 50% milk line inspections should be done every 3 days.
• On dry fields there is a lot of variation between soil forms and potentials, and even more where contours are concerned.

It remains essential to still do the DM test in an air fryer or microwave oven. This confirms how accurately the milk line has been determined. The air fryer test is a standard method used to determine DM, and usually takes 30 to 35 minutes per sample.

Good quality and homogeneous silage

Good quality and homogeneous silage increases feed intake. The quality and homogeneity reduce pH fluctuations in the rumen. Variable pHs cause the animals to spend more time ruminating to stabilise the pH, which leads to reduced feed intake and poorer growth or low milk production. Ask yourself whether, if you were the animal, you would eat the more palatable or the less palatable feed. Your main goal as a manager is to ensure maximum feed intake.

Cutting time window prediction

What is the purpose behind using Granular Link to predict the cutting time window?

• It is non-negotiable to get better quality and more homogeneous silage in the bunker.
• It reduces the logistical disadvantages of field evaluations with regard to milk line determination.
  1. You are not going to throw away physical milk line determination, but rather only do it on the predicted dates.
  2. By doing so, you are building in an additional check for yourself to ensure that the model is correct.

The future of silage production

The model uses satellite images from day 1, but predictions only occur from the 60th day after planting. In most cases, we start cutting ultra-fast hybrids in South Africa from 106 days, which means the model determines the estimates within the next 50-70 days.

The recommendation takes into account the following:

• The maize hybrid planted (growth height)
• The available field information (NDVI and other indices)
• Effective root depth (soil depth)
• The weather data during the growth cycle
• Plant stand
• Irrigated or dry field

Recommendation

Taking everything into account in the previous paragraph, a cutting window is recommended with reference to different DM (dry matter) values.

What are the advantages of using the model?

• You can start planning your cutting time in the comfort of your office without spending unnecessary time on the field itself.
• Milk line determination is then only used as confirmation of the model’s prediction.
• Cutting contractors can be booked in advance; the quality of the silage will be increased by cutting it closer to the correct DM%.
• 32% DM may be just too wet to start cutting, but it helps to improve timely planning.

Dry field recommendation

The future of maize farming in South Africa lies in being at the cutting edge of technology and staying there. Yield increases occur through small positive increments. That is why we are switching to precision farming, to get the most out of our available resources.

Why go through all the costs and challenges of precision farming, and consider silage cutting time to be less important? It is time to form a fresh point of view about silage handling.

One such example is using Granular Link to predict your cutting time date – this improves the homogeneity within the silage bunker.

Figure 2. The original field cut as a whole.

Figure 3. The same field, divided into cutting dates, based on growing conditions, to get optimal DM% and homogeneity in the bunker.

Figure 4. The same field, divided into cutting dates according to satellite data.

In the example (Figure 4), there is no big difference between the contours, but the steeper the contour and the greater the soil differences, the more obvious the differences between the contours will be. It is clear that if you were to start cutting at 35% DM, you would rather start by cutting Block A, then Block C, before cutting Block B, since Blocks A and C lose moisture faster due to environmental and soil differences.

The disadvantage of such a precise cut is that the silage bunker must be close to the field, and that you must use your own transport to the bunker. If you are far away, and/or you use a contractor for transport, the field is predicted as a whole. If mycotoxins are important to you as a milk producer, it will be easy to make the mind shift.

Challenges

It is essential to collect as much data as possible from different maize hybrids in the model – especially the number of days to flowering, because the flowering date is your safety net to ensure that the recommendation is correct. Existing maize hybrids are being replaced very quickly by newer hybrids these days, each with its own growth characteristics.

Pioneer is busy determining VT and R6 data in the silage centres in the country, which will undoubtedly improve future estimates.

For more information, contact Pioneer at info.rsa@pioneer.com