Irrigators, rotating

The current meter is generally used for measuring velocities in open channels such as rivers and irrigation channels. There are two types, the cup meter and the propeller meter. The former is more widely used. It consists of six conical cups mounted on a vertical axis pivoted at the ends and free to rotate between the rigid arms of a... 

Elimination of Demand for the Slashing and Burning of Forests through Maintenance of Soil Fertility (e.g., through crop rotation, irrigation). 

Ricefields exclude upland rice. The physical area is calculated from the sum of irrigated rice (51 Mha of which 47% is double- or triple-cropped with rice and 33% under rice-wheat rotation), rainfed lowland rice (54 Mha) and deepwater rice (4 Mha). The riceland of China is taken to be all temperate. 

Witt C, Cassman KG, Oik DC, Biker U, Liboon SP, Samson MI, Ottow JCG. 2000. Crop rotation and residue management effects on carbon sequestration, nitrogen cychng and productivity of irrigated rice systems. Plant and Soil 225 263-278. 

Results after the first and second rotation. The systems varied in fertiliser (synthetic or organic), winter cover crop and irrigation frequency (Cunapala and Scow 1998). 

Food production in the last few decades has been improved greatly by applying chemical fertilizers, irrigation methods, rotation of crops, and plant-breeding practices. Despite these new technologies for increased food production, the crop losses caused by insect pests, pathogens,... 

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