Tractors, tubewells and cropping intensity in the Indian Punjab
量化了印度旁遮普邦拖拉机和管井对种植强度的影响，发现两者均与更高的种植强度相关，且自有拖拉机优于租赁，管井效应大于拖拉机。
This paper quantifies the cropping intensity effects of tractors and tubewells in the Indian Punjab. In addition to the conventional measure of cropping intensity, a new index, which takes account of the time duration of crops grown, is specified. The advantage of tractor ownership vs. hiring the machine is also assessed as are the effects of farm size and agro‐climatic zones. Relative to bullocks and canal irrigation, tractors and tubewells are respectively found to be associated with higher cropping intensities, as measured by both indices. Owned tractors have an advantage over hired ones and the effect of tubewells is substantially greater than of tractors.