Die Bodenkultur - Journal for Land Management, Food and Environment
Contribution to product safety of silage maize by differential pre-harvest measurement
Maize production trials carried out in Germany from 1999–2004 were used for statistical analysis of the optimum date for silage maize ripeness.
The Silage maize Ripeness Index (the ratio of dry matter content of maize grains to dry matter content of stover) is more suitable for the determination of harvest date, yield maximum and silage maize quality as the dry matter content of the plant. The analysis is cheaper as well as not so material and time-consuming in comparison to the dry matter content of the silage maize of different hybrid maize populations and environments. Ensilage optimum and yield maximum correspond almost with the physiological ripeness of silage maize and are close to the grain dry matter content of 60–65 %, to the dry matter content of stover under 24 % and a ripeness index from 2,5 and higher.
Recently, the silage maize harvest depends on dry matter content of maize plants. This can result in grain ripening rates less than 55 % and low starch as well as energy contents.
The dry matter content of the silage maize is at a certain ripeness of grain and/or of starch only expression of aging of the stover.
The stover has, together with the grain, a strong influence on the dry matter content of the whole plant maize. On these locations the crop should be harvested before reaching the optimum of ripeness and yield maximum. Therefore only hybrids with a long harvesting time, high starch storage and displaying a high digestibility of plant cell wall with slow drying of the stover, should be grown in the future.
The Silage maize Ripeness Index (SRI) is, for whole plant maize, better than the Whole Plant Maize Ripeness Index (SRZ) for the choice of a hybrid in Germany. The dry matter content of grain in interaction with the dry matter of stover are better than dry matter content of the whole plant maize as ripeness indicator in the production of maize.
SRI is also suitable for use in scientific trials as a standard for the harvesting time and for better “stay green” characteristic.
It is a strong correlation between the Silage maize Ripeness Index (SRI) and Silage maize Nutrient Index (SNI) or Silage maize Quality Index (SQI) respectively as indicator for the physiological reaction of starch and metabolizable energy in the rumen as well as for the choice of a hybrid.
Key words: Forage maize, Silage maize Ripeness Index, product safety, Silage maize Quality Index, Grain/Stover- Ripeness Method