This week the drought is having a negative effect on our thermophilic compost piles but a positive effect on our vermicompost (worm compost piles).
Each thermophilic compost pile is turned 5 times during its “life cycle” (40-60 days on average) before being applied by spreading in the orchard. The piles are watered when they are constructed and after that they are watered only when necessary (as long as the moisture content is 40-60%). This approach saves water and energy (transportation of the water tank). Moisture is required by the microorganisms present in the compost for life processes (reproduction), heating and cooling, place to live and to move. Dry compost (less than 40% moisture) may contain smaller numbers of microorganisms and is difficult to re-wet.
Usually, winter rains help in keeping the piles moist. This winter there has been no rain so far, the nights are cold and the days are relatively mild. The piles lose water at night because of the cold and wind (like food in our refrigerators) and by evaporation during the day. This week, three of the “older” piles have suddenly dropped in moisture content (below 40%). We also analyzed the biology in these piles (quantification of various indicator microorganisms) and the numbers were on the low side. The decision was taken to water the piles one more time and we hope that the biology will improve but that temperatures will start going down.
On the other hand, the vermicompost piles are watered twice a day for 5 minutes using drip irrigation. At night the piles are insulated from the cold by a covering of straw. During the day, the sun heats the piles to comfortable levels (in the winter). If the winter is rainy, the piles can become too wet and the worms can “drown”. So, this winter in some respects is very good for worm composting.