Sunday, January 15, 2017

Making Silage in Vichada, Colombia

by Dexter B. Dombro

Worker harvesting elephant grass.
Amazonia Reforestation and La Pedregoza are making as many natural fertilizers as possible for our tree cultivations. To do so requires quality manure, this is why we maintain a stable with Zebu cattle. Obviously, the nutritional content of the feed our cows eat has a bearing on the quality of that manure, so we are looking at ways of enhancing their diet during the dry season (January through to April), when native grasses dry up and are little better than cellulose. One solution for improving animal feed is to make silage, so this article explains the process we are employing at our plantation.

Feeding elephant grass into chopper.

First off, our definition of the word silage is as follows: fresh grass or other green fodder chopped, mixed with molasses, compacted and then stored and fermented in airtight conditions, to be used as animal feed when climatic conditions are appropriate. What makes silage important? Basically, it retains up to 80% of the nutritional value of the fresh grass or fodder, whereas hay or dried fodder will lose up to 80% of its nutritional value, so silage is much better for one’s cattle. Needless to say, as a result the quality of the manure from silage is better than from dried fodder when preparing compost or other fertilizers.

Worker dwarfed by elephant grass.

We plant a variety of grasses at La Pedregoza. The most productive one is African elephant grass (Pennisetum purpureum), which can grow to be 4 meters tall, spreads well in the pasture and produces up to 40 metric tons per hectare per year of biomass. While it propagates by seed, it is more efficient to plant elephant grass using stem cuttings when the plant has matured. The grass is tolerant of poor soils and low rainfall, which is another plus in some tropical locations. This high rate of biomass production means that elephant grass is not just a useful animal feed, but could also be ploughed into poor soils to enhance the soil’s organic material, carbon and nitrogen content.

Brachiaria pasture at La Pedregoza.

There are two other grasses we cultivate in our silvopastoril project, both of which have reasonable protein contents and can be used for silage. Brachiaria decumbens is bitter tasting, while Brachiaria humidicola is sweeter and better nutritionally when cultivated with other legume plants. Obviously having a variety of grasses and fodders enhances the cows’ menu and the quality of the manure. Nevertheless, in this article we are going to concentrate on making silage with elephant grass.

Filling trailer with chopped grass.
We harvest using machetes, much the way sugar cane is harvested. The bundles of elephant grass are then carried to and fed into the chopper, which in turn is powered off the tractor’s PTO, and which casts the chopped grass into a wagon. We find that one wagon filled is about 1,200 KGs of chopped material, which is a reasonable amount for one day’s silage making. 1,200 KGs represents 2 hours of harvesting and chopping with 2 to 3 farm hands.  Any more harvested and chopped, and one may end up with material that is already dry and less nutritious a day later.

We use a silage press to remove air.

We use a 2-barrel manual silage press, which allows for a fast work flow. Each barrel accommodates a heavy gauge plastic bag that can take 40 KG of chopped grass. This means that our daily target is the production of 30 bags of silage weighing some 40 KG each. Mixing the chopped grass with molasses and then stuffing and sealing the bags, as well as depositing them in the storage shed takes a further 4 hours with the labour of 3 farm hands. We like 40 KG bags of silage, because they are easy to carry and transport, as well as easy to stack and store.

Mixing grass, molasses and cattle sale.
The mixing of the silage is very important, as an even mix ensures good fermentation. We add 10 KG of molasses to every 200 KG of chopped grass, as well as about 1 KG of cattle salt. The mixing is done with shovels and rubber boots, until the molasses is well distributed throughout the grass. Next, we fill the bags, putting first 10 KG of mix into the bag and then compressing it, before adding more material and compressing it. The compressing is done in order to remove as much oxygen as possible.

The press removes all air before sealing the bag.

Making silage and its fermentation is an anaerobic process. If air is left in the bag or mix, the silage will go bad and it will smell horrible, at which point it is only useful as compost. The secret of good silage is therefore to remove as much air as possible before sealing the silage bags. Within days the storage area will have a nice aroma, similar to beer or wine making.

Silage bags are stored away from direct sun.
Once the bags are filled and compressed, they are sealed tight with a cord and taken to the storage area. In tropical areas, it is best to store the silage in a shaded area, away from direct sunlight. The silage is ready within 15 days of being bagged, and can last for up to one year, though we generally use it within 4 to 6 months of it being bagged. By looking after the bags and keeping them out of the sunlight, we are often able to reuse the bags, which can reduce costs. Silage produced in the farm is very cost efficient, as one can save by not buying third party products, and of course there is no transportation cost to the farm gate either

Happy cows pooping for better compost!

The process above can also be used to make Bokashi, which is a Japanese fermented type of compost that is much richer in nutrients and quite a bit quicker to produce. The difference is that one would also have to prepare Bokashi bran and mix that bran in with the chopped material, manure, kitchen scraps and molasses.  Other than that the process is pretty much identical. Recipes for making Bokashi bran can be found on the internet, using wheat bran, rice water, sawdust or other ingredients.

© 2017 Plantacion Amazonia el Vita S.A.S.

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