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The soil infiltrability of hill-slope is important to such studies and practices as hydrological process, crop water supply, irrigation practices, and soil erosion. A new method for measuring soil infiltrability on hill-slope under rainfall condition with run off-on-out was advanced. Based on water (mass) balance, the mathematic models for soil infiltrability estimated from the advances of runoff on soil surface and the water running out of the slope were derived. Experiments of 2 cases were conducted. Case I was done under a rainfall intensity of 20 mm/h, at a slope gradient of about 0° with a runoff/on length (area) ratio of 1 : 1. Case II was under a rainfall intensity of 60 mm/h and a slope of 20° with a runoff/on length (area) ratio of 1 : 1. Double ring method was also used to measure the infiltrability for comparison purposes. The experiments were done with soil moisture of 10%. Required data were collected from laboratory experiments. The infiltrability curves were computed from the experimental data. The results indicate that the method can well conceptually represent the transient infiltrability process, with capability to simulate the very high initial soil infiltrability. The rationalities of the method and the models were validated. The errors of the method for the two cases were 1.82%/1.39% and 4.49%/3.529% (Experimental/Model) respectively, as estimated by comparing the rainfall amount with the infiltrated volume, to demonstrate the accuracy of the method. The transient and steady infiltrability measured with double ring was much lower than those with this new method, due to water supply limit and soil aggregates breaking down at initial infiltration stage. The method can overcome the short backs of the traditional sprinkler method and double ring method for soil infiltraility. It can be used to measure the infiltrability of sloped surface under rainfall-runoff-erosion conditions, in the related studies.

Using indoor artificial simulated rainfall, rainfall use efficiency, wetting front shape and soil moisture content were analyzed to investigate water distribution and rainwater use of interval coverage on Lou soil slope land. The results showed that with area ratio increased, under same rainfall intensity and slope, rainfall use efficiency decreased, and the maximum rainfall use efficiency of uncoveraged treatment was 58.93%. There was no significant difference in wetting front shape and the maximum depth of each treatment, and the maximum depth was 17cm, which located at the conjunction point of coverage area and infiltration area, which all were higher than that of CK. Soil profile moisture distribution of each treatment accorded to general rule, which gradually decreased from surface to deeper layer. Water content at the conjunction point was slightly higher than other points. Average soil moisture content in infiltration area decreased with area ratio increased, but they were all higher than that of CK. The results also showed that coverage measures could increase actual acceptable rainfall and soil water storage of infiltration area. But how to determine appropriate area ratio to improve rainwater use efficiency under different experimental conditions still need to be further investigated.

Nitrification-denitrification is an important mechanism of N loss in paddy soils. How to prevent such loss is a matter of primary importance (1–4). The present article deals with the effect of Nitrapyrin (2-chloro-6-(trichloromethyl)-pyridine) on nitrification, nitrogen loss and percentage of fertilizer nitrogen recovery by crops, and on crop yield.