the a-frame is an important tool in contour farming but it has limitations

The A-Frame is a tool consisting of wooden frame in the shape of capital A with which contour lines are located manually in sloping agricultural lands.

A-Frame for sloping agricultural lands.An A-Frame made of bamboo

In sloping agricultural land technolgy (SALT) which was popularized in the Philippines by the Mindanao Baptist Rural Life Center (MBRLC) in Bansalan, Davao del Sur, the tool is essential.

It is fabricated with two wooden or bamboo legs tied on top and with the tips of a wooden (or bamboo) crossbar tied about the middle of both legs. A plumb bob substitute (for convenience  a piece of rock wrapped in plastic sheet and tied to a string) is hung from the top to just below the crossbar.

With this tool, spots on the ground with more or less same elevation are marked with stakes. Consequently, the stakes will define a contour line which, if viewed from the top, will either be in the shape of a straight line, or a line that curves, or a combination.

In SALT, the contour lines serve as guide in the placement of hedge crops like ipil-ipil (Leucaena leucocephala (Lam.) de Wit) or madre de cacao, also known as kakawate (Gliricidia sepium (Jacq.) Walp.). In between adjacent contour lines is a wide strip intended for the planting of a short maturing cash crop.

Limitations on the Use of A-Frame

An A-Frame entails high labor cost. Assuming that the farm is 100 meters from boundary to boundary across the slope and the leg-to-leg distance of the frame is 1 meter, it will take more than 100 leg-after-leg flipping of the frame. The number of times that the legs are moved cannot be simply calculated arithmetically by division because likely the contour line will be that of a curve.

Considering that the forward leg needs to be moved up or down to align the weighted string to the center of the crossbar, the operation is likewise time- consuming.

Moreover, its use is quite impossible in lands with heavy vegetation like cogon (Imperata cylindrica (L.) Raeusch.) or where woody shrubs like hagonoy (Chromolaena odorata (L.) R.M.King & H.Rob.) will hamper the flipping of the tool and prevent it from finding the spot with the same elevation as that of the first staked ground. 

Even slashed weeds which are still fresh may serve as thick ground cover and become barrier against any leg finding the ground.

Unless there are farm workers clearing ahead to remove barriers or the entire farm is first cleared to remove obstacles, the tool maybe useless.

In addition, plowing of the land a few days prior to staking proved to create difficulty. Personal experience by the author revealed that unbroken clods of soil (furrow slices) become a hindrance in finding the original level of the land.

(Ben G. Bareja, July 7, 2018)

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