When is time to sow for the silo
When planning for a summer sowing of crop that is going to be put in a silo a few doubts arise regarding the ground’s quality and weather (plenty or insufficient rain). Defining these aspects is of vital importance when it comes to the selection of the type to be sowed. (Based on the experiments done by the Agricultural Engineers Luis Romero, Oscar Bruno and Eduardo Comerón and the Chemical Licensed Mónica Gaggiotti.)
How is the experiment done?
On November of 1998 sugary hybrid foddered sorghum was sowed (Beefbuilder R), in furrows 0,70m apart with a density of 20 plants per lineal meter.
Three different cutting times were studied: Early (December 29th), Medium (January 26th) and Late (March 20th). In each one of them, and also in the sprouts from the first two, the following was evaluated:
- The production of green material
- The percentage and production of dry material
- The morphologic composition and plant quality
- Gross protein (GP)
- Neutral detergent fiber (NDF)
- Acid detergent fiber (ADF)
- Digestibility "in vitro" of dry material (DIVDM)
- Total non-structural carbohydrates (TNSC)
Furthermore, experimental silos were done for the first cut, evaluating nutritious and ferment qualities.
In tables 1 and 2, the results in fodder production and quality are shown.
Table 1
Status and date of the cut |
Height (m) |
GM/ha (kg) |
DM (%) |
DM/ha (kg) |
Composition stem leaf ear |
|||
| First Cut | ||||||||
| Early | (29/12) | 1,56 | 37000 | 11,4 | 4187 | 55 | 45 | 0 |
| Medium | (26/01) | 2,56 | 78200 | 21,7 | 16982 | 75 | 16 | 9 |
| Late | (20/03) | 2,67 | 66800 | 28,9 | 19284 | 66 | 12 | 22 |
| Sprout | ||||||||
| Early | (15/03) | 2,21 | 47800 | 19,4 | 9283 | 59 | 17 | 24 |
| Medium | (15/03) | 0,95 | 11200 | 10,0 | 1123 | 49 | 51 | 0 |
Table 2
Plant’s quality at different moments during the cut.
| Status and date of the cut | GP % |
NDF % |
ADF % |
DIVDM % |
TNSC % |
||
| First Cut | |||||||
| Early | (29/12) | 10,5 | 63,6 | 40,6 | 57,3 | 7,8 | |
| Medium | (26/01) | 7,0 | 61,6 | 40,8 | 57,2 | 6,9 | |
| Late | (20/03) | 6,4 | 57,9 | 33,1 | 63,2 | 29,4 | |
| Sprout | |||||||
| Early | (15/03) | 7,0 | 61,1 | 45,7 | 53,3 | 17,8 | |
| Medium | (15/03) | 8,9 | 72,0 | 48,3 | 51,2 | 6,4 | |
In all analyzed parameters, there were important differences in the three studied moments for the first cut, with oscillating productions between 4.000 and nearly 20.000 Kg DM/hectare. The percentage of dry material was very low for the December 29th cut (11.4%), better was for January 26th (21.7%) and close to 30% for March 20th (Late). The same happened with the sprouts production on the two analyzed dates, it was high on the early (little more than 9.000Kg DM/ha) and low on the second (approximately 1.000Kg DM/ha)
The maximum production was achieved with the late cut date (19.284 Kg DM/ha)
Of the quality parameters analyzed, only the GP showed an improvement with early cuts.
On table 3, the chemical composition and the ferment characteristics of the product in the silos are shown.
Table 3
Chemical composition and fermentation characteristics of the crop, at different moments of the cut.
| Status and date of the cut | DM % |
GP % |
NDF % |
ADF % |
DIVDM % |
NH3/NT % |
Ph % |
|
| First Cut | ||||||||
| Early | (29/12) | 14,5 | 9,7 | 65,7 | 42,8 | 55,6 | 33,9 | 4,9 |
| Medium | (26/01) | 19,8 | 7,8 | 63,7 | 42,2 | 56,0 | 30,3 | 4,8 |
| Late | (20/03) | 28,2 | 7,9 | 58,2 | 35,2 | 61,5 | 8,9 | 3,8 |
The analysis of the chemical composition of the crop in the silos showed the same values of those in the plant it self. Furthermore, the crop from the early and medium states presented low dry material and poor conservation (high values of Ph and nitrogen ammonia over total nitrogen).
Some results from the experiments
The maximum production of dry material is achieved when only one cut is performed, during the latest date.
The early cut dates do not improve the quality of the plant nor the crop. Furthermore, they show a low dry material content, which means poor conservation.
The cost of crop in the silo increases when more than one cut is performed: less production, doubles the cost when chopped, per superficies, etc.
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