This should enable it to determine about 10 or 11 classes of soil moisture.

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And in some of the world's great winemaking regions, such as California, geological variations mean that the ability of soil to retain or lose moisture can change within distances of a few metres.

ECONOMIST: Winemaking and radar

They will look, too, at the amount of ice in the ground, and the temperature and the moisture of the soil.

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The university team studied 18 rock panels and looked at the effects of factors such as soil moisture, salinity and height.

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Meteorologists say the dry conditions in the Midwest started with a lack of snow, which usually replenishes soil with moisture.

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It also carries the risk of producing an inaccurate picture of the overall distribution of moisture, as the spots chosen for sampling may be considerably damper or drier than the soil just a few metres away.

ECONOMIST: Winemaking and radar

Working organic amendments such as compost into your soil will help it drain faster and retain a more even level of moisture.

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Bolstered by increasing soil moisture, longer growing seasons, warmer winters, and the fertilizing effects of more atmospheric carbon dioxide, crop production continues its long and impressive run of ever-increasing yields as global temperatures warm.

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