Two years back, I got around 10Kgs of turmeric seeds from our friends Raghu/Nisha of http://www.greenlocal.org/. That time I arranged two farm laborers and got around 6 raised beds and put the turmeric. When there was heavy grass later in the raised bed, weeded once. Later in the summer harvested and yield was OK, even though no input was given. During harvesting, I wanted to retain the raised bed, but this didn't happen. It was all dismantled. Some of the turmeric was powdered in the mill and sold and some was given to friends and relatives. Feedback was good and felt very happy about it.
In the next season, I wanted to do turmeric, but after calculating the labor cost, thought of doing it without using much effort. That time, I had got that area tilled. So instead of putting in raised bed, I just put the seeds in directly in the soil and then sunhemp was sown all around. Sunhemp grew well and in between turmeric also had come up. But later in the summer I was not able to locate the turmeric plants since it had already dried and there was mulch all over and land was too dry to harvest.
This year after rains, turmeric plants came up and I picked up most of them and I could see that yield was very poor. But I wanted to atleast save the seeds, so planted in area through mulch. But all these plants are kept together so that harvesting is easy. Later put one raised bed and planted some turmeric and applied some dried cowdung over this. But the raised bed creating was back breaking, it is lot of effort, so decided that at any cost will retain that raised bed to reduce the effort.
Some time back an article came about one Mr. Pappachan in Kannur who cultivates ginger without using any manuring. He has mainly pepper and ginger and he uses Mucuna as cover crop. When the ginger is harvested, he leaves one portion there so that in the next season it comes up. This looks to be a real natural farming sequence for tubers. He is a national innovation award winner and this details can be seen here - http://nif.org.in/upload/innovation/4th/329-papachchan-style-of-pepper.pdf
For an initial boost, raised bed may be OK, but later I am planning to retain it and reuse for tuber cultivation and in between planning to grow some green manure for keeping the fertility. Some pictures of my raised beds
Photo of Pappachan whose article came out in Karshakashree
Now a days, it became the norm, I don't make raised beds, rather keep them and plants turmeric at the start of the rainy season. Recently while harvesting taro, I kept 12 of them back with mulch applied and could see that they are coming up well. So this makes me think, during harvesting itself, it can be planted back and saves the effort.
These are the lines from Natural Farming Source book by Masanobu Fukuoka - "As for potatoes,once these are planted in the orchard, they will grow each year from the same pot, crawling vigorously along the ground to lengths of five feet or more and never giving into weeds. If just small potatoes are dug up for food and some tubers always left behind, there will never be any want of seed potatoes"
Today there was a call from Francis (Pappachan) asking how is my ginger cultivation going on. I told him, I just cultivate only turmeric, so he wanted me to try ginger in the following way.. Place the ginger pieces after cutting the weeds and put some dried cowdung over it and cover it with mulch not very thickly. Now as the mulch decomposes, keep adding new mulch and continue this for 3 times. No need to apply any manure, he says without applying any manure, the crops has better disease resistance. I have promised him, will do a trial plot for ginger in this way.