Precipitation Storage Efficiency Research Articles

Soil Nitrogen Status as Affected by Tillage, Crops, and Crop Sequences

AbstractConservation tillage practices, including no‐till (NT), reduce soil erosion and increase precipitation storage efficiency, but may decrease available soil N. We conducted studies at two sites to determine the comparative effects of NT and stubble mulch (SM) on the N supplying capacity of Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls) cropped to continuous wheat (Triticum aestivum L.) (CW), continuous grain sorghum [Sorghum bicolor (L.) Moench] (CS), wheatsorghum‐fallow (WSF), and wheat‐fallow (WF) sequences. AT one site, accumulation of NO3‐N in the surface 1.2 m (in kg ha−1) was CW NT ‐ 20, CW SM ‐ 37, CS NT ‐ 28; CS SM ‐ 24, WSF NT ‐ 34, WSF SM ‐ 52, WF NT ‐ 57, and WF SM ‐ 60. Tillage significantly affected N accumulation only on the WSF sequence. Nitrate ‐N moved deeper into the profile under NT than under SM, indicating that differences in the root zone may have resulted from differential leaching rather than from differential nitrification. Yields under no‐till and stubble mulch were similar except on continuous grain sorghum where nitrogen deficiency was encountered and stubble mulch outyielded no‐till.

CJ90-32. Similitude analysis of thermo-elasto-hydrodynamic lubrication performance of large hydraulic turbine thrust bearings : By Xue Yongkuanet al. (Xi'an Jiaotong University, Xi'an, China). Chinese J. Mech. Engng26, No. 3 (June, 1990), pp. 1–11

Field experiments were carried out to study the effects of different soil management practices on the water balance, precipitation use efficiency (PUE), and crop yield (i.e. winter wheat and peanut) on a loess soil near Luoyang (east edge of the Chinese Loess Plateau, Henan Province, China). Field plots were set up in 1999 including following soil management practices: subsoiling with mulch (SS), no-till with mulch (NT), reduced tillage (RT), two crops per year (i.e. winter wheat and peanut, TC), and a conventional tillage control (CT). The field plots were equipped to monitor all components of the soil–water balance except evapotranspiration, which was computed by solving the water balance equation. The results showed that although soil management had smaller influence on the magnitude of the water balance components than did precipitation variations, small influences of the applied soil management practices on water conservation during the fallow period can greatly affect winter wheat yield. SS increased consistently precipitation storage efficiency (PSE) and PUE over the 5 years compared to CT except during the wettest year. NT also had a noticeable effect on postharvest water storage during the fallow period; however, the influence on yield of NT depended on the amount of precipitation. TC lowered the winter wheat yield mainly due to the unfavorable soil moisture conditions after growing peanut in summer; however, the harvested peanut gained an extra profit for the local farmer. No matter which kind of soil management practices was adapted, PSE never exceeded 41.6%, which was primarily attributed to high evapotranspiration. From data of five consecutive agricultural years between 2000 and 2005, it could be concluded that SS resulted in the highest PSE, PUE and crop yield. TC also showed promising results considering the economic value of the second crop. NT performed slightly less as SS. CT gave intermediate results, whereas RT was the worst alternative.

Fallow method influences on soil water and precipitation storage efficiency

Summer fallowing is practiced in the Great Plains of the U.S.A. in order to store soil water, control weeds, make nutrients available and stabilize crop yields. Soil water storage and precipitation storage efficiencies on chemical and stubble-mulch fallow plots were compared for three 14-month fallow periods for a winter-wheat-fallow rotation ( Triticum aestivum L.) and three 21-month fallow periods for spring-wheat-fallow rotation in the northern Great Plains to determine during which seasonal segment the fallow method might influence soil water storage. The experiment was conducted on a glacial till Williams loam (fine-loamy mixed, Typic Argiboroll) from July 1981 to April 1985. Soil water contents to a depth of 1.70 m were measured, using the neutron scatter technique, for seasonal segments during the fallow period. Soil water storage was similar from harvest to spring on chemical and stubble-mulch fallow plots. The over-winter to spring segment resulted in the most consistent precipitation storage efficiencies (33.3–71.1%). Soil water storage differences as a result of a fallow method are most likely to occur during summer fallow for 14-month winter-wheat-fallow rotations and during the second overwinter for 21-month spring-wheat-fallow rotations. Soil water storage for the entire fallow period was greater on chemical fallow than on stubble-mulch fallow in two out of three 14-month winter-wheat fallow periods and in one out of three 21-month spring-wheat fallow periods.