旱地桑“优耕法”试验续报

小区试验和大田生产多点试验进一步证明,旱地桑应用“优耕法”这一管理技术,具有一定保持地力和保水防旱的效能,维持对桑树养分的供给,有利于提高肥效,促进桑树生长,有效地增产桑叶,改善叶质,提高养蚕成绩,据测算投入与产出比达到1:4.37,比造桑造肥法管理的桑田高0.65,增产效果相当显著,是旱地桑获得高产、优质、高效益的有效措施。

旱地桑“优耕法”试验与研究(再报)——大田生产扩大应用效果

在1993年小区试验、1994年继续小区试验并开展大田生产多点表证取得增产、增收,效益显著的基础上,1995年着重于大田生产扩大表证应用。从125个管理区1669户共215.77公顷旱地桑的应用,获得比常规法平均1/15公顷,桑叶增产20.31％,多养蚕种0.95张,产值增29.50％,投入与产出比高0.39—0.52,其结果与1993—1994年是相一致的。大田应用效果进一步证明:旱地桑代耕法具有提高肥效,促进桑树生长,增产桑叶,改善叶质,提高养蚕收成,增加经济效益,是旱地桑田达到“两高一优”的有效措施。

旱地桑“优耕法”试验初报

针对我县旱地桑园由于管理方法不当造成产叶量低,经济效益差的问题,根据桑树生理、生长和我县的气侯特点探索旱地桑园管理的新技术开展“优耕法”(即深耕施肥,秋期地面复盖)的试验,初见成效,下半年桑叶增产62.19％,万头蚕产茧量增4.2％,茧层量增7.9％,公斤茧价增5.6％,达到了省力、高产出、高效益的目的,符合我县的实际易被蚕农所接受,正在扩大试验示范,继续完善提高。

Study on Absorption Law of Nitrogen,Phosphorus and Potassium and Proper Nitrogen Application in Chuanxiangyou 9838 under No-tillage Cultivation

The aim of the study is to investigate the absorption laws of nitrogen, phosphorus, and potassium, and proper nitrogen application in Chuanxiangyou 9838 under no-tillage cultivation. Five nitrogen application treatments were designed to analyze the absorption laws of N, P and K, and to discuss the effects of different N fertilizer application amounts on yield and yield composition factors of Chuanxiangyou 9838. The results showed that gross nutrient absorption in Chuanxiangyou 9838 was greatly varied at different developmental stages under rice-rape rotation with no-tillage. The maximum N absorption in Chuanxiangyou 9838 appeared at jointing stage followed by heading stage, thirdly the tillefing stage ; the P absorption in Chuanxiangyou 9838 presented the consecutively slight increase during seedling stage and mature stage ; the K absorption in Chuanxiangyou 9838 was mainly conducted from jointing stage to heading stage, during which K absorption accounts for 73.4% of the total absorption in whole developmental stage. Consequently, N fertilizer should be applied earlier （ before jointing stage）, P fertilizer is suitable as base fertilizer and application of K fertilizer should be preferably conducted at early-middle period. When the yield reached 11 t/hm^2, the optimal N application amount in Chuanxiangyou 9838 was about 165 kg/hm^2.

Effects of Tillage Management on Infiltration and Preferential Flow in a Black Soil, Northeast China

The impacts of no-tillage （NT） and moldboard plough （MP） managements on infiltration rate and preferential flow were characterized using a combined technique of double-ring device and dye tracer on a black soil （Mollisols） in Northeast China. The ob- jective of this study is to evaluate how tillage practices enhance soil water infiltration and preferential flow in favor of soil erosion con- trol in the study area. The steady infiltration rates under NT management are 1.6 and 2.1 times as high as those under MP management in the 6th and 8th years of the tillage management in place, while the infiltrated water amounts under NT management are 1.4 and 2.0 times as high as those under MP management, respectively. The depth of methylene blue penetrated into NT soil increases from 43 cm in the 6th year to 57 cm in the 8th year, which are 16 cm and 19 em deeper than those in MP soil, respectively. The results of morphol- ogic image show that more biological macro-pores occur in NT soil than in MP soil. These macro-pores play a key role in enhancing preferential flow in NT soil, which in turn promotes water infiltration through preferential pathways in NT soil. The results are helpful to policy-making in popularizing NT and have the implications for tillage management in regard to soil erosion control in black soil region of China.

Optimized Design for the Plow of a Submarine Plowing Trencher

The plow of the submarine plowing trencher is one of the main functional mechanisms, and its optimization is very important. The design parameters play a very significant role in determining the requirements of the towing force of a vessel. A multi-objective genetic algorithm based on analytical models of the plow surface has been examined and applied in efforts to obtain optimal design of the plow. For a specific soil condition, the draft force and moldboard surface area which are the key parameters in the working process of the plow are optimized by finding the corresponding optimal values of the plow blade penetration angle and two surface angles of the main cutting blade of the plow. Parameters such as the moldboard side angle of deviation, moldboard lift angle, angular variation of the tangent line, and the spanning length are also analyzed with respect to the force of the moldboard surface along soil flow direction. Results show that the optimized plow has an improved plow performance. The draft forces of the main cutting blade and the moldboard are 10.6% and 7%, respectively, less than the original design. The standard deviation of Gaussian curvature of moldboard is lowered by 64.5%, which implies that the smoothness of the optimized moldboard surface is much greater than the original.

Performance of Moroccan Wheat Cultivars under Tillage Systems and Water Regimes

The superiority of wheat grain yield under no-till has been reported by many authors, and others reported significant interaction between wheat cultivar and tillage system for grain yield and other related traits. Hence, new breeding initiatives are needed to introgress favorable traits into wheat and other crops in areas where no-tillage is being adopted. The identification of such traits is solely possible via the assessment ofgermplasm under no-tillage. Moreover, Moroccan wheat breeding programs are carried out solely under conventional tillage system whilst the conservation one is becoming widely adopted. So, the ultimate objective of this research is to find out if the used wheat commercial cultivars behave differentially under no tillage system and to propose the use of appropriate cultivars for the appropriate tillage system and to implement a breeding program specifically for no tillage system. The experiment has been carried out during 2006-2007 at Douyet （F6s）. Cultivars have been sown according to a strip-split plot design. At maturity, yield, yield components and related traits have been recorded. The results indicated that both water regime （WR） and variety （Vat） had a highly significant effect on all measured traits. In contrast, tillage system （TS） had similar effect on yield, grains m-2, biomass, and plant height, but had no effect on harvest index, 1000-kernel weight and heading date. The TSxVar interaction has been significant to highly so on all traits except on heading date. The magnitude of the interaction for grain yield was more important under irrigated treatment than under rainfed one. On the whole, No Tillage yielded more grains than conventional one. Moreover, Achtar and Areal （bread wheat cultivars） and Marjana and Marzak （durum wheat cultivars） yielded more under No-Till. The significant interaction between TS and Var paves the way for the implementation of a breeding program under no till system.

Where Are Potential Regions for the Reallocation of Wheat in the Context of Chinese Land Fallow and Food Security Policies? Findings from Spatio-temporal Changes in Area and Production Between 1990 and 2014

One of the aims of the recently initiated land fallow policy is to encourage winter wheat abandonment in order to recover the groundwater environment of the North China Plain (NCP);although this also threatens a national secure supply of this crop,as the NCP is the major wheat producing area in China.It is therefore necessary to consider regional wheat reallocation in order to meet the twin challenges of production and water conservation.An evaluation of spatiotemporal changes in wheat area and production across China in recent years may shed light on the regions that have the potential for reallocation;such trends are analyzed in this study using agricultural statistical data.Three over-arching principles are proposed that reallocation must be naturally suitable,economically feasible,and socially acceptable,and together with the result of the spatiotemporal analysis,two continuous areas are recommended as potentially suitable for wheat reallocation-alongside the Huai River and the cold region of northeastern China.We also present strategies to improve wheat yields as well as policies for farmers,aiming to encourage the reallocation of wheat to the regions highlighted in this study.