Quick Answer. Neo-Malthusian theory holds that population growth is exponential and that human population growth can easily outstrip its food resources if not held in check with artificial birth control measures. It differs from traditional Malthusian theory in the proposed birth control solution.
Terrace farming is when farming is done on manmade terraces that have been built into slopes. When humans transform a slope into a series of flat surfaces, they form terraces. Crops are then grown on these flat surfaces rather than on the slope, preventing crops from sliding down the slope over time. The image below is of rice paddies grown on terraces. By building these terraces, water flows down and accumulates in each terrace. If the terraces did not exist, rainfall and water would flow from higher elevations down the hill/mountain, carrying important soil and nutrients with it. Building terraces prevents this from happening.
One way that farms can control runoff is by planting cover crops when the fields do not have anything planted in them. A cover crop is a crop that is planted mostly during the winter when most other plants cannot grow. Farmers plant these crops to help stop soil erosion. Cover crops help stop erosion because these plants hold the soil in place with their roots, which means that wind or water cannot wash the soil away. Cover crops also help to increase the organic matter in soil, which increases soil health.