To maintain the fertility/ nutrients in the soil, addition of compost is a common method. While composting speeds up the natural cycle of transforming energy and returning it to the soil, it can be very labour intensive to shift the compost to different areas, specially on a mountain. Also, if the land area is big, it will take a lot of biomass to generate compost for the entire land. This biomass will too a lot of time and energy to grow.
One of the more effective methods suggested by Rico and Martin to maintain the fertility of the soil is to grow green manure on fallow terraces or in rotation with grains and vegetables.
If we cut the plants before they flower and turn them into the soil, they will decompose into humus and improve the soil fertility and structure. Such plants are called green manure. Also since they maintain a cover on the soil for the their growing period, there are also sometimes referred to as living mulch.
Choice of plants:
1. Fast growing plants generate more biomass in less time.
2. Succulent plants are preferred to woody ones, since they decompose faster.
3. Plants with different root systems tend not to compete with each other and break the compacted soil.
4. A mix of plants from leguminacae and graminacae family are generally preferred to maintain a balance between the carbon and nitrogen being returned to the soil. (Legumes add nitrogen while cereals add carbon due to their high starch content).
Based on our observations of what grows well, we are using mustard, radish, peas and several kinds of beans. THough we are sure more plants can be added to this list in the future.
To grow the green manure, we need seeds. Buying the green manure seeds is expensive and also not sustainable in the long run. Our focus was to first multiply the green manure seeds. The green manure was not chopped and turned into the soil. Rather, the plants were allowed to seed and the seeds were preserved for future use.
To propagate the seeds, we used seedballs.
A Seedball is basically a dry lump of soil protecting seeds inside them. These balls can be thrown away or rolled down to the place we wish to grow the seeds. Continuous watering or rains will dissolve the soil around the seeds and give them a medium to establish themselves. The use of seedballs eliminates tilling or any other kind of land preparation for sowing, and thus protects the micro life in the soil and saves time and labour.
The seedballs were thrown on the terraces by hand a day before rain was anticipated. The rains washed the seedballs, breaking them open and allowing the seeds to sprout. Once these seeds grew into mature plants, they were left to flower. The pods containing the seeds were left to dry (turn brown) and then harvested and dried for a couple of weeks before being opened. The seeds were stored in a cool, dark place until turned into seedballs again for multiplication.