Come along to three farms whose stories tell how - and how not - to meet humanity's need for food:
* The faltering Soviet farm, being pushed by a splashy new government drive to put more food on citizens' tables.
* The bountiful American farm, producing so much food that farmers ironically are suffering low prices.
* The aspiring third-world farm, progressing faster than had been expected but lagging in some places - conspicuously Africa - where mouths to feed are many.
Last week came the latest signs of Soviet failure and US success. The estimate for this year's Soviet grain crop was sharply reduced, making it the fourth poor harvest in succession. The estimate for the US winter wheat crop was revised to top last year's record, instead of declining as predicted.
Next week the focus will be on the third-world farm when the United Nations World Food Council holds its ministerial meeting in Mexico. The main subject will be the growing gap between supply and demand in Africa.
In some respects the Soviet farm remains a third-world farm. It needs some of the same solutions that already aid the American farm: simple things such as good barns and roads. Peasants often leave a substantial part of a crop in the field because handy storage is not available. And Moscow's new program is trying to encourage small farms to compensate for the inefficiencies of collectivized farming. It stands by the latter but promises more freedom for local officials through new district ''agro-industrial associations.''
There is a question of land reform here that could be instructive to the third world. The Soviet peasants expected the revolution to bring land reform by taking from the large holders and giving to them. Instead, the land soon was taken from the peasants. The government has still not won back their full energies, despite incentives.
In some third-world countries land reform remains necessary. It is important enough to be a condition of some international aid.
So too is effective pricing of agricultural products, not so low as to discourage production, not so high as to increase hunger. The World Bank finds that, for all the problems of supply in low-income countries, the commonest cause of undernutrition is ''a straight-forward lack of purchasing power.''
Here is where the three farms - Soviet, American, and third-world - are linked not only to each other but to all the world's farms. For the low prices now being received by US farmers are due to the state of demand not only within the US but in the world. The effort to prevent wild variations in prices leads to perennial efforts to stabilize them through such means as commodities reserves.
At the same time the efforts of various countries to increase food exports can have adverse effects on meeting their own food needs. So-called ''export cropping'' can bring in income to buy food, to be sure. But it can also distort land use by diverting acreage unwisely to specialized export crops and requiring import of foods previously grown at home.
Some think the US Caribbean Basin Plan might cause problems by prompting countries to plant more sugar, for example, to take advantage of duty-free entry to the US. Legislation is being contemplated to require evidence that participants protect their own food security when they hike export cropping. In the abundant US itself, the temptation rises to exhaust the land for short-term profit instead of husbanding it as a resource for the world.
Yes, weather can have an influence on all of the above. But it cannot be blamed for the misuse or neglect of the earth that humanity more and more knows how to prevent.