Maize plots in practice: estimating chopping time
In practice, we see a large variation between maize plots, with both early and extremely late sown plots. This difference is clearly visible in cob setting: early-sown maize has well-developed cobs, while for late-sown maize it is still uncertain whether the cobs will mature. For late-sown maize, the harvest time is already definitely shifting towards the end of October. So correctly estimating the ideal chopping time is a challenge. Therefore, we share some valuable tips to help you do so.
Step 1: Assess the dry matter content of the plant
Determine the dry matter (DM) content of the plant. Cut a few plants above the first node, kink the stem, wring it out and estimate how much moisture is still coming out.
Entire plant still green and moisture running out of stem: 18% DM
Plant ¾ green and stem still moist: 21% DM
Plant half green and stem practically dry: 24% DM
Plant ¼ green and stem completely dry: 27% DM
Plant no green parts left (crop seems completely dead): 30% DM
Step 2: Assess the dry matter content of the cob
The dry matter content of the cob can be estimated using the milk line in the grain. The milk line is the separation between the solid starch and the milk part. It is best to assess the milk line on a grain from the middle of the cob. For maximum starch utilisation, wait until the blacklayer (cork layer) begins to discolour. This is a sign that the kernel is maximally filled with starch.
Step 3: Combine and determine dry matter content, the most important step this year!
Due to the variation in sowing date, there is a wide spread in the plant-cob ratio this year. Early-sown maize this year has a shorter plant but a heavier cob, with a ratio of about 40-60. Late-sown maize, on the other hand, has a longer plant but a thinner cob, with a ratio of about 60-40. An accurate estimation of this ratio is crucial for determining the right dry matter content.
Let's see this in practice with the following example:
DM content of the plant: 21%
DM content of the cob: 55%
We now calculate the DM content of total maize with different plant-cob ratios:
Plant-cob ratio = 50-50: 38% DM total maize
Plant-cob ratio = 40-60: 41% DM total maize
Plant-cob ratio = 60-40: 34% DM total maize
So we see that with the same DM content for both plant and cob, there can still be a difference of 7% DM in the total maize for silage. So it is very important this year to estimate the correct plant-to-cob ratio on your maize plots.
