No-till planting method is widely used for maize-wheat two-crops-a-year area in the North China Plain. However, cruel soil conditions, especially the large number of maize stalks which are hard to cutoff covering, often cause an unsatisfying planting quality. Based on the authors' previous investigation, ultrahigh-pressure (UHP) waterjet is capable to solve this problem and obtain qualified seedbeds. Thus, a UHP waterjet assisted furrow opener for no-till seeder was designed. Field tests showed that double-disc furrow openers worked well with UHP waterjet, since the sharpened disc blades could help to cut soil and residue, meanwhile, minimize soil disturbance. Response surface method (RSM) was used to investigate the relationship among forward speed, waterjet pressure, jet impingement angle and anti-blocking performance (stalks cutoff ratio and depth of soil cutting), and a Box-Behnken three-factor design was used to identify the optional operation parameters. A total of 17 combinations were conducted, and the results showed all three operation parameters significantly affected anti-blocking performance. Stalks cutoff ratio and depth of soil cutting increased with the increase of waterjet pressure, jet impingement angle, and decreased with the increase of forward speed. The optimization analysis indicated that when waterjet pressure was 267-280 MPa, jet impingement angle was 80.2° to 90.0° and forward speed was 4.00-4.42 km/h, the overall performance of UHP waterjet assisted double-disc furrow opener for no-till seeder was maximized. Stalks cutoff ratio could be above 95% and no blockage occurred. This study may provide a new approach and reference for the anti-blocking technology of no-tillage seeding.

In order to promote the winter wheat yield and guarantee seeding quality in double-cropping system, no-tillage or reduced tillage planting modes with different row spacing have been implemented to result in different levels of yield. A three-year (2012-2015) field experiment was conducted on the experimental farm at Zhuozhou of Hebei Province in North China Plain to compare winter wheat yield from the two planting modes: wide-narrow row space planting mode (WN) and uniform row space planting mode (UR) Both planting modes were performed under reduced tillage conditions with straw mulching. The results showed that in North China Plain WN had positive impacts on crop yield, yield components, leaf area index (LAI) and intercepted photosynthetically active radiation (IPAR) index. Comparing with the UR, IPAR and LAI index for WN were enhanced by 4.8% and 5.2%, respectively. The average yield for WN was 7.2%, significantly greater than that of UR under the same quantity and density. In addition, for WN mode, machinery could pass through with less blocking under large amount of straw mulching, which largely improved tillage efficiency and potentially popularized the conservation tillage technology in North China plain. It is therefore recommended that wide-narrow row space planting mode (WN) combined with reduced tillage and straw mulching be more suitable for conservation tillage in double-cropping pattern areas in North China Plain.

In order to promote the winter wheat yield and guarantee seeding quality in double-cropping system, no-tillage or reduced tillage planting modes with different row spacing have been implemented to result in different levels of yield. A three-year (2012)(2013)(2014)(2015) field experiment was conducted on the experimental farm at Zhuozhou of Hebei Province in North China Plain to compare winter wheat yield from the two planting modes: wide-narrow row space planting mode (WN) and uniform row space planting mode (UR) Both planting modes were performed under reduced tillage conditions with straw mulching. The results showed that in North China Plain WN had positive impacts on crop yield, yield components, leaf area index (LAI) and intercepted photosynthetically active radiation (IPAR) index. Comparing with the UR, IPAR and LAI index for WN were enhanced by 4.8% and 5.2%, respectively. The average yield for WN was 7.2%, significantly greater than that of UR under the same quantity and density. In addition, for WN mode, machinery could pass through with less blocking under large amount of straw mulching, which largely improved tillage efficiency and potentially popularized the conservation tillage technology in North China plain. It is therefore recommended that wide-narrow row space planting mode (WN) combined with reduced tillage and straw mulching be more suitable for conservation tillage in double-cropping pattern areas in North China Plain.

Large amounts of crop stalks left in the field as a result of conservation agriculture cause blockage during no-till planting. To solve this issue, pure waterjet was used to cut off the maize stalks so that the rear furrow opener could pass through without blockage. In this investigation, an experimental study on depth of cut, which was the main performance indicator of pure waterjet on cutting maize stalks, was presented. A full factorial design with 200 tests was implemented with respect to three operation parameters, that is traverse speed, waterjet pressure, and standoff distance were considered as variables. An analysis of variance (ANOVA) was carried out in order to determine the statistical significance of individual operation parameters. Using multilinear stepwise regression analysis, a model to predict the cut of depth from the predicted pure waterjet operation to cut maize stalks was then developed. All three operation parameters significantly influenced the cutting performance. Moreover, the results indicated that depth of cut increased with the increase of waterjet pressure, the decrease of traverse speed, and decrease in standoff distance. Waterjet pressure provided major contribution to depth of cut, followed by traverse speed, then standoff distance, which was demonstrated by both ANOVA and regression analysis. The experimental results showed that when the standoff distance was closer than 10 mm and waterjet pressure was 280 MPa, all maize stalks specimen could be cutoff thoroughly. With the consideration of field operating conditions, waterjet pressure of 280 MPa or higher and 10 mm to 15 mm standoff distance were recommended for maize stalks cutting. This analysis provided a realistic approach for the optimization of the ultra-high pressure pure waterjet parameters in maize stalks cutting, which could be used to relieve the occurrence of straw blockage in no-till planting.