lending money against the volume of the harvest.
This means the crop yield is declared or estimated and the sum value of the credit is determined on this basis. This is like lending money against the purchase of a house, where the property value is estimated or valued and the amount of credit is thus set.
Good luck.

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Note added at 2006-03-19 14:42:41 (GMT)
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I would translate the full text as follows: \'a 10-million trade credit facility was taken up to provide a loan to beet farmers against the volume of the harvest. Furthermore, separate farms were financed with sugar\'.

Firstly, it does read that the credit was taken up to lend to the beet farmers. Therefore, I do not see from the context why \'torgovy kredit\' should be translated in any other way.
As for the last sentence, it may seem odd, but it does say that individual farms were financed with sugar. Unless the remaining text dictates otherwise, I would say that the farmers farm the beet, and receive a payment in kind, similar to the PIK programme in the United States. The following link gives an overview of this programme. I hope this helps.

www.michiganfarmbureau.com/farmnews/transform.php?xml=20000...