Monday, 14 October 2013

On Rice and Wheat rotations, nutrient management, and Lake Taihu in Jiangsu Province….

Untitled by Soil & Water Science
Untitled, a photo by Soil & Water Science on Flickr.
We have just spent the last 2 days in the vicinity of Suzhoe and Wuxi in the Lake Taihu catchment in Jaingsu Province. We were visiting as part of the Defra SAIN (Strategic Agriculture Innovation Network) collaboration between the UK and China Governments. Our aim was to visit local rice-wheat rotations with a view to learning about how the agricultural systems ‘worked’ and in particular focusing on the nutrient management. On Friday 11th October 2013 we visited Xingeng Village, to the Northeast of Wangting Town. On the following day we visited a Demonstration site west of Wuxi, the Sandongqiao Village Demonstration Site. On the 11th, firstly were shown some mature rice that was due for harvest later in the autumn. Of course rice production involves flooding the field and that happens earlier in the year. I understand there is a top dressing of fertilizer input at time of sowing, and that this is applied when the padi is flooded. This is intriguing as there is potentially considerable potential for direct nutrient transfers to water at times of flooding. There is also potential for groundwater transfers through potentially cracking clay soil. Additionally, as there is the potential in this extreme wetting and drying to drive nutrient cycling and accelerate nutrient mobilization from soil in these circumstances – it would be interesting to investigate this hypothesis. I would be interested to see how much nutrient was lost in detached soil or sediment around times of sowing when the crop is immature. We asked questions of the team about the nutrient management and as far as we could understand they seemed to have a very agronomic centric view, inasmuch as they spoke of monitoring the system wholly in terms of fertilizer and recycled manure inputs. When questioned about transfers to water they did not seem to have a sense of the potential kg/ha losses, nor any sense of the hydrologic dynamics. There was not any evidence of measuring water flow so therefore I cannot see how they have any sense of nutrient flows to water. On the Saturday at Sandongqiao we met the impressive Prof Yudong Li (Shanghai Jiantong University) who appeared to have a much greater sense of the importance of flows to water. However, the Sandongqiao site is only in its infancy and although the rotation has the potential to offer some useful data in the future.

In summary:
•There are no data on flows to water and there seems to be a lack of emphasis on this
•The systems appear to be constrained and driven by agronomic production with only an emerging regard for losses to the environment
•It reminds me of my own work in the UK in the early 1990s, with systems driven by soil P tests and fertilizer levels, occasional concentration in water. The next step is that they need to learn to determine the nature of the losses to the water, including the hydrological flows and dynamics, not just the concentrations in water.
•A great ‘problem’ for these systems is the density of the population; therefore one cannot manage the water quality without a sense of the agriculture combined with the human inputs. There are governance and communication challenges here
•The work at Sandongqiao is promising and I see analogies with other studies in the past.

My photos from this trip can be viewed here.


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