Ukrainian grain exports have fallen to 6.82 million metric tons so far in the 2023/24 July-June season, from 8.99 million tons in the same period of 2022/23, agriculture ministry data showed.
The ministry said on Wednesday that 153,000 tons of grain were exported in the first three days of October 2023, compared with 297,000 tons a year ago.
The ministry gave no explanation for the fall.
Traders and agricultural unions have said that Ukrainian Black Sea ports being blocked and Russian attacks on Ukrainian ports on the Danube River are the main reasons for lower exports.
The exported volume included 3.4 million tons of wheat, 2.7 million tons of corn and 625,000 tons of barley.
Ukraine has traditionally shipped most of its exports through its deep water Black Sea ports.
A deal brokered by the United Nations and Turkey allowing such exports collapsed in July as Russia declined to recognise it, saying its demand that sanctions be lifted on its grain and fertiliser exports had not been met.
Earlier, Ukraine's navy said that 12 more cargo vessels were ready to enter a fledgling Black Sea shipping corridor on their way to Ukrainian ports and 10 were preparing to leave, as Kyiv steps up a push to defy the de-facto Russian blockade.
Those figures appeared to indicate an increase in the amount of shipping traffic set to use the temporary "humanitarian corridor" for cargo vessels.
Russia, which has a much more powerful and bigger naval fleet in the Black Sea, pulled out of a deal in July that had allowed wartime Ukraine to safely ship food products out through what is traditionally its main export corridor.
Ukraine can export limited volumes through small river ports on the Danube and via its western land border with the European Union.
Ukraine is expected to harvest 79 million tons of grain and oilseed in 2023, with 2023/24 exportable surplus totals of about 50 million tons.
(Reporting by Pavel Polityuk; Editing by Alexander Smith)