Jacky Foo wrote:
> In your response to John Harris, you wrote:
> >Pig manure as input of digester came from a pig sty, in which
> >pigs were fed with the mixture of bran and treated chicken manure (30-60%).
>
> The Guquan village case study is therefore a comparison of the use of
> digested pig slurry and chicken manure. Though independently, each pond
> experiment may yield data on the yield of fish, I do not consider that the
> data useful for comparison of the two ponds for the following reasons
> (a) the type of inputs are different (i.e. one is pig manure and the other
> is chicken manure+grass)
> and secondly
> (b) the pond size/depth are different

Dear Friends:

The comparative study of fish farming by slurry and chicken manure plus small
amounts of grass was part of Research of Rural Ecological Engineering in Ququan, Nanjing.

In general, chicken manure is the best among various manure to be put into
fishponds for aquaculture. However, from the hygiene point of view, it is
better to use slurry from anaerobic fermentation. That's why they compared the
effects on fish farming by chicken manure and slurry. Even if treated chicken
manure was used to feed pig and then pig manure was used to input into
digester, the results could show that slurry was better than chicken manure
for fish farming. Of course from nutrient flowing analysis point of view, it
is not ideal comparison. If somebody or some donor agency can support this
kind of theoretical study, we'd like to repeat the study.

So far as different size and depth of fishponds are concerned, the experiments
could be conducted in cooperation with the fish farming production unit. It is
due to research fund limit.

> I wish to put these final questions to you on the Guquan village experiments.
> In the manure fed pond (3,260 m2 size)
> (1a) how much fish fingerlings (total weight) was put into the pond ?
> (1b) how much fish was harvested (total weight)
> (1c) how much feed (chicken manure, grass, etc) was put into it ?

1a Fish fingerlings total weight input as in Table 2 was 167.30 kg/mu
1b 394.80 kg gross weight harvested 227.50 kg net weight harvested
1c in Table 1
Chicken manure was input by 30.645 t/ha and grass by 0.93 t/ha

> In the slurry fed pond (913 m2)
> (2a) how much fish fingerlings (total weight) was put into the pond ?
> (2b) how much fish was harvested (total weight)
> (2c) how much slurry was put into it ?
>
> Can you please explain what Table 1 is trying to show and please elaborate
> the meaning of the column titles ? The numbers dont add up correctly too ?

In slurry pond
Fish fry and fingerlings were stocked by 85 kg/mu and 893 kg/mu gross weight
harvested and 808 kg/mu net weight harvested. No contradiction between the figures.

Li Kangmin