Thursday, July 03, 2008

Tilling and soil erosion: sugarcane farms

I was born and grew up in Negros Occidental province in central Philippines. It is the sugar plantation capital of the country. In my past travels to almost all 81 provinces in the country, I would say that in terms of land utilization, no other province could beat it because one will hardly see vacant or idle land there. Almost all lands are fully utilized, for residential/commercial/industrial use, and planted with sugarcane or any other crops (coconut, banana, fruit orchard, a few rice land). This makes me feel proud of my province.

Huge tracts of land planted mainly to sugarcane, from midway of mountains down to the lowlands, means huge volume of harvested sugarcane being transported from the farms to huge sugar milling companies. During peak harvest and milling season, hundreds of over-loaded 6-wheeler trucks, up to long 18-wheeler trucks, all carrying several tons of sugarcane per truck, would be seen plying the provincial roads everyday. This plus bad public governance where the quality of newly-constructed or newly-repaired roads is often suspect, explains for the bad road network in the province.

I was not too observant of “topsoil level” before. After going through several pages of “No Till Farming” book published by the World Association for Soil and Water Conservation (WASWC), I became more aware of the threats to topsoil erosion by regular tilling and plowing of agricultural lands.

Sugarcane farms are perhaps the most tilled lands in the Philippines and other countries, after rice farms. But in the latter, rice farmers use only small hand tractors, if not farm animals like “carabao” (water buffalo) or bulls. In addition, rice fields are terraced so the ground is flat, that even water is impounded and trapped up to a certain height; hence, soil erosion is minimized and controlled. In sugarcane farms, they are using regular tractors which are big and heavy, so the plowing of the soil is deeper and wider. Many sugarcane fields are also not on flat soil, rather on hilly and rolling terrain. So when there is heavy rain and the soil has just been tilled and not yet planted to sugarcane, the volume of eroded soil can be huge.

In my recent visit to my province just last week, I observed that a number of sugarcane fields are several inches below the average ground level. Some are even 1 or 2 feet lower, especially those on non-flat terrain and those beside a canal. I surmised that the difference between current sugarcane fields’ level and the normal soil level, say on the shoulder of the provincial road, or those planted to bananas and coconut trees, is the amount of soil that has been eroded through time. If this difference or depth is only a few hectares wide, there could be no problem much. But if it covers thousands of hectares, then the problem can be big.

So, if a big volume of topsoil has been eroded through time, where does it go? By the law of gravity, the eroded soil go to lower areas – in creeks and rivers, ultimately into the ocean. The immediate result is that many creeks have disappeared after soil and small stones have covered their deeper portions, and everything were shallow and flat. There is still small water flow coming from upstream springs, but some lowland natural springs were covered and disappeared.

A similar thing happened in rivers. Many rivers’ depth have declined, meaning the rivers have become shallower, with regular deposit of eroded soil and rocks from the uplands and midlands. But rivers’ width have increased on average, as strong flash floods would “eat up” unstable and soft river banks, and as the rivers are now shallower. Mangrove forest species and related vegetation, like “nipa” and palms would help in stabilizing otherwise unstable river banks.

I think not all sugar planters are into yearly plowing of their farm, but I assume that their number is small. With the current expensive fuel prices though, I would assume that some sugar planters will be forced to reduce their tilling, say once every 2 cropping season or every 2 years, or even once every 3 years. Planting of sugarcane tops through manual boring will not only be a cheaper alternative, but also more sustainable in both short- and long-term as the slightly compacted soil is left undisturbed by heavy tractors and deep plowing.

As sugar planters slowly realize the virtue of no-till farming, aided mainly by expensive fuel prices, I hope that topsoil erosion will be minimized in my province. Although high prices and profitability of sugarcane for biofuel production could spur more sugar planters to continue the old ways of regular, annual deep tilling of their sugarcane farms, since high fuel prices for tractor plowing can be offset by high profit for biofuel production. Ultimately, it is the realization of the environmental value and long-term economic benefits of no-till farming that will convince many sugar planters to take this agricultural practice.