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前段时间智种网 NOVOSEED 公号发布了一些列英文资料，大家反馈非常好，为了让更多的人看到和了解这些资料，我们招募了翻译志愿者，将这些资料翻译成中文，在此，再次感谢这些老师的支持和参与。欢迎更多的老师加入翻译团队。 智种网翻译小组长期招募翻译自愿者，为了让更多的人了解和学习国外的先进技术和知识，需要将一些实用且重要的英文资料（包括主要农作物：玉米、水稻、大豆、小麦和油菜等）翻译成中文。期待您的加入，如您想加入翻译小组，请加微信 leafsword，并备注翻译。  For 70 years, beginning in1866, national corn grain yields in the U.S. were essentially flat (Fig. 1) andaveraged only 26 bpa (bushels per acre) during that entire 70-year time period.The absence of noticeable yield improvement throughout all those years isremarkable given that farmers of the day were essentially also plant breederspracticing a recognized form of plant breeding (mass selection) as they savedthe best ears from each year’s crop for planting the next. 随着美国开始摆脱 1930 年代的大萧条和重度沙尘暴，美国玉米种植者开始用双交种的新技术取代传统的自由授粉玉米品种。几年内全国玉米产量明显发生了巨大变化。在 1937 年至 1955 年期间，平均玉米产量从年产量无增长变为大约每年 3/4蒲式耳/英亩的产量增长（图1）。玉米产量提高速度的变化代表了生产能力的巨大飞跃。 As the nation began to emergefrom the Great Depression and Dust Bowl years of the 1930’s, U.S. corn growersbegan to replace their traditional open-pollinated corn varieties with the newtechnology of double-cross hybrid seed corn.Within a few years, a significantshift in national corn grain yield was evident. During the period 1937 – 1955,average corn yields changed from no annual yield improvement to an annual rateof gain equal to roughly three quarters of a bu per ac per year (Fig. 1). Sucha shift in the rate of improvement in corn grain yield represented a quantumleap shift in productive capacity. 20 世纪 50 年代中期，随着更多地采用单交种和其他新的生产技术，包括机械化、除草剂和无机肥料（特别是氮肥），玉米年产量的增长出现了第二次飞跃。从1956 年左右开始，年产量增长急剧变化，从每年产量增加 3/4 bpa 转变为每年产量增加近 2 bpa，并在随后的 55 年中保持在该速度（图1） A second quantum leap in theannual rate of yield gain in corn occurred in the mid-1950’s with the greateradoption of single-cross hybrids and other new improved production technologiesincluding mechanization, herbicides, and inorganic fertilizers (especiallynitrogen). Beginning around 1956, the rate of annual yield gain dramaticallychanged from about three quarters of a bu per ac per year to nearly 2 bu per acper year and has remained at that rate in the succeeding 55 years (Fig. 1). 地球人口的指数增长要求我们提高全世界玉米和其他主要粮食作物的增产率。如果年平均增产率保持在每年略低于 2 蒲式耳/英亩的水平，那么在 2086 年之前，预计全美国平均玉米产量不会达到 300 bpa；这与经常提到的承诺相去甚远，即生物技术将在 2030 年使美国全国玉米平均产量达到 300 bpa。 The exponential populationgrowth on this planet mandates that we increase the rate of yield improvementin corn and other major food crops around the world. If the average annual rateof yield improvement remains constant at just under 2 bu per ac per year, thenachieving a national average corn yield of 300 bpa would not be expected tooccur until about 2086; a far cry from the often quoted promise thatbiotechnology will result in a national U.S. corn grain yield average of 300bpa by the year 2030. 为了 2030 年能实现这一崇高目标，必须从明年开始实现年增产率的又一次飞跃，这将使我们在未来 19 年的年增产率达到 7.5 bpa。在玉米生产史上这种巨大的产量飞跃将是前所未有的。与近年来农业机构和玉米种子产业对转基因玉米性状对产量贡献的宣传相反，几乎没有证据表明玉米增产率已经开始了第三次飞跃（图1）。 To reach that lofty goal by 2030, another quantum leap shift in the rate of annual yield gain would have tooccur beginning NEXT YEAR that would take us to an annual increase of about 7.5 bu/ac/yr for the next 19 years. Such a quantum leap shift in yield improvementwould be unprecedented in the history of corn production. Contrary to the hypeand hoopla over transgenic corn traits by the farm press and seed corn industryin recent years, there is little evidence that a third quantum leap shift incorn productivity has yet begun (Fig. 1). 另一个令人不安的事实是：相对于产量的变化趋势，过去50多年来年相对增产率一直在稳步下降（图2）。在 20 世纪 50 年代中期发生第二次巨大跃迁后不久，相对增产率约为每年 3.5%。从那时起每年的产量基本以 2 bpa 的速度增加。然而由于目前的平均粮食产量明显高于 20 世纪 50 年代，因此目前的相对年增产率仅为每年 1.2% 左右。  Another disconcerting fact isthat relative to trend yields, the annual relative rate of yield gain has beensteadily decreasing for the past 50 years (Fig. 2). Shortly after the secondquantum leap shift occurred in the mid-1950’s,the relative rate of yieldimprovement was about 3.5% per year. Since then the absolute rate of yield gainper year has remained unchanged at 2 bu per ac per year. However, since today’saverage grain yield is significantly higher than those in the 1950’s, therelative rate of annual yield gain today is only about 1.2% per year. 300 蒲式耳/英亩的产量现在可以实现！ 300 Bushels per acre isachievable today! 除非技术很快出现奇迹般的进步，到 2030 年实现全美平均玉米产量 300 bpa 的目标很可能难以实现，但个别种植者在全国玉米产量竞赛中证明，他们可以用现在的技术和品种达到 300 bpa 的产量（NCGA，2010）。 Even though the goal ofachieving a national AVERAGE corn yield of 300 bpa by 2030 is likely out ofreach unless a miraculous improvement in technology occurs soon, it is truethat individual growers have demonstrated in national corn yield contests thatthey can produce 300 bpa with today’s technologies and genetics (NCGA, 2010). 此外，玉米超过 300 bpa 产量所需的生理基础条件在现在并非不可实现。目前杂交种的潜在粒数很容易达到 1000 粒。这相当于一个果穗有 18 行，每行 56 个籽粒。如果每英亩 30000 株（5000株/亩 ）时果穗可以保持上面的大小，如果籽粒重量可以保持在每蒲式耳 85000 左右个籽粒，56 磅（25.4公斤）的重量（适度的籽粒重量），那么这些产量构成因素相乘起来就相当于 356 bpa 的产量潜力！ Furthermore, the physiological yield components necessary to produce a 300 bu crop are notterribly out of reach today. Potential ear size is easily 1000 kernels withtoday’s hybrids. That would be equal to an ear with 18 kernel rows and 56 kernels per row. If (admittedly a big IF) that ear size could be maintained ata harvest population of only 30,000 plants per acre and IF kernel weight couldbe maintained at about 85,000 kernels per 56 lb. bushel (a modest kernel weight),those yield components would multiply to equal a yield potential of 356 bpa! 玉米产量超过300 bpa的秘诀 Thesecret to producing 300 bushel corn 考虑到玉米的产量潜力已经超过 300 bpa，在农场的常规生产中是什么阻止了这个产量结果的实现？答案很简单，一旦种下了种子，作物就会受到一系列产量限制因素的影响，大多数是降低产量潜力的逆境。因此，提高产量的秘诀就是注意识别影响产量的因素，特别是每个农场的不同因素。只要成功地做到了这一点，后续就能更有针对性的采取农艺管理措施，缓解阻碍产量的逆境因素，加强那些促进高产的因素。很简单吧？ Giventhat the yield potential of that bag of seed corn is already 300 bpa, thenwhat is preventing all of us from routinely producing those high yields on ourfarms? The answer to that question is simple… Once that seed is planted, that crop is subjected to a season-longarray of yield influencing factors, most of which are stresses that reduceyield potential. So, the secret to improving yields on your farm is simply tosharpen your focus on identifying the yield-influencing factors specific to thefields you farm. Once you have successfully done that, then you are betterequipped to identify the appropriate agronomic management strategies toalleviate those factors holding back your yield and, perhaps, enhance thosefactors that promote high yields. Pretty simple, eh? 是高深的“火箭技术“还是简单的农艺常识？ Rocketscience or common sense? 许多人在提高产量上的问题是，他们总想寻找解决问题的“妙招”或“一招制胜”的办法。比如他们阅读了一些农场杂志文章，文章里描述了一个人在农场里所做的改进使玉米产量增加了 20 bpa，于是他们认为应该在自己的农场尝试同样的操作。或者听了附近县的农户介绍，在作物上使用了一些乱七八糟的增产药剂有效果，于是便跑到当地的零售商处去购买这类产品在自己的农场尝试。再或者在会议上记住了一些从未去过他们农场的大学专家们提出的最佳管理方案（BMP），并准备明年也采用这些方案。问题在于，我们需要投入时间和精力来确定特定于自己地块的重要产量限制因素。正如前面所说，一旦能成功地确定自己地块中的产量限制因素，就能更有针对性的使用相应的农艺管理措施，缓解限制产量的因素，同时尽可能提高促进高产的因素。这不是高深的“火箭科学”，这是需要付诸努力的基础常识性工作，再加上扎实的农艺知识。 The trouble with the way many folks go about the business of improving yields ontheir farms is that they always look for the “silver bullets” or the “one-size-fits-all” answer to their problems.They read farm magazine articles that highlight what one guy has done inTimbuktu that supposedly resulted a 20 bpa jump in his corn yields and figurethat they ought to try the same thing on their farm in northwest Iowa. Theylisten to the testimonials of someone in the next county over that used Bob’s High Yield Snake Oil & Emolument on his crop and rush over to their local crop input retailer to buy some of the stuff to try ontheir farm. They take notes on the best management strategies presented at a crops conference by some guy from Purdue Universitywho has never been on theirfarm and make plans to adopt those BMPs for next year’s crop. The problem or challenge, you see, is that you need to invest your own time andeffort to identify the important yield limiting factors that are specific to your own fields. As I stated earlier, once you havesuccessfully identified the yield limiting factors specific to your production fields, then you are better equipped to identify the appropriate agronomic management strategies to alleviate those factors holding back your yield and, perhaps,enhance those factors that promote high yields. It ain’t rocket science. Itis hard work and common sense, coupled with a sound knowledge of agronomicprinciples. 影响产量的因素 (YIFs) Yieldinfluencing factors (YIFs) 识别特定地块中影响产量的主要因素并不容易。首先，YIFs 对产量的影响可以是负面的，也可以是正面的，都要注意。这些因素可能每年都在某一特定地块发生，也可能不会。这些因素通常与其他因素相互作用来影响产量。想想高温 干旱 土壤压实的综合影响。YIFs通常能对不同的作物产生不同的影响，与土壤类型、土壤质地、排水条件包括天气条件相互作用，这些因素通过影响构成谷物产量的四个组成部分来影响产量。YIFs发生的时间与作物生长阶段有关，这很大程度上决定了对这些产量构成的影响，因为YIF会在生长季的不同时间发生（图1）
·· 每英亩株数（密度或苗数） ·· 每株穗数（空杆级别） ·· 穗粒数（潜在的实际的） ·· 穗行数 ·· 行粒数 ·· 粒重 The process of identifying the YIFs that are important to your specific fields isnot an easy one. First of all, these YIFs canbe either negative or positive in their effects on yield. Pay attention toboth. These YIFs may occur every year in a given field… or they may not. TheseYIFs often interact with other YIFs to influence yield. Think about thecompounded effects of heat drought soil compaction. TheseYIFs often affect different crops differently. For example, most of us do not worry about gray leaf spot disease in soybeans. Frankly, as a corn guy, I don’t worry about soybeans anyway, but that’sanother story. These YIFs often interact with soil type / texture / drainage conditions. These YIFs almost always interact with weather conditions. Ultimately, the effects of YIFs on corn yield are equal to their effects on the four components that constitute grain yield.The timing of the occurrence of YIFs relative to crop growth stage greatlydetermines their effect on these yield componentsbecause they develop at different times throughout the season (Fig. 1). ·· Plants per acre (population or “stand”) ·· Ears per plant (degree of barrenness) ·· Kernels per ear (potential vs. actual) ·· Kernel rows per ear ·· Kernels per row ·· Weightper kernel 一旦你列出可能影响你农场玉米产量的 YIFs，你会觉得有很多因素都要考虑到，那从哪开始呢？ 如果对于特定地块你已经种植了一段时间，那么你自己的经验对于确定 YIFs 非常重要。以经验为依据就可以会排除一些因素，列出一个简短的 YIFs 列表。 Once you sit down to list thepossible YIFs that may influence corn yields on your farm, you will easilyreach the conclusion that there must be a gazillion YIFs to consider. Where doyou begin? If you have farmed aparticular field for a while, your own experience in that field is invaluableto identifying the YIFs specific to that field. You can probably come up with ashort list of obvious YIFs based on that alone. 在接下来的种植季尽量对作物整个生长过程中发生的情况进行全面记录，不要只在播种或收获时下地，要定期查看地块。当然也可以雇一个巡田人员帮你巡田，但你自己巡田可能会掌握更多的信息。 In future cropping seasons,strive to keep thorough notes on what happens with the crop during the entiregrowing season. Don’t just plant it and come back at harvest. Visit your fieldsregularly. Sure, you can hire a crop scout to walk your fields for you, butthere is a lot to be said for you walking your fields yourself. 用好私营和公立部门的农业技能、知识。与农资零售商的销售或技术人员保持密切联系。考虑雇用一个独立的作物顾问来服务。 别忘了你所在的区域大学里的资源。如果你还不知道你当地州立大学里玉米或大豆农艺专家的名字，这就有点说不过去了！可以在以下网站中找到他们的信息。这些专家还可以帮你与当地更了解具体情况的专业人士取得联系。 http://www./experts/CornSpec.html http://www./experts/soyspec.html Take advantage of theagronomic skills and knowledge of both the private and public sectors. Workclosely with the sales or technical agronomists from your crop input retailers.Consider hiring the services of an independent crop consultant. Don’t forget the Extensionresources available at your own land-grant university. You say you don’t knowthe name of your state’s Extension corn or soybean agronomist? Shame on you!You can find them in the following Web directories. These specialists can alsoput you in contact with other, more specific, content matter specialists atyour land-grant university. http://www./experts/CornSpec.html http://www./experts/soyspec.html 阅读来自中西部各大学的农业时事通讯了解生长季的最新情况。其中大部分文章会链接到我的Chat'n Chew Café网站：http://www./cafe。（我知道在这推广我自己的网站有点厚脸皮，但我能说什么？） 花时间浏览两个关注玉米生产问题的优秀大学网站： 普渡大学的知识宝藏：http://www./news/archive.html 爱荷华州立大学罗杰·埃尔莫尔：http://www.agronext./corn Stay up to date during thegrowing season by reading Extension newsletters from around the Midwest. Youcan find most of them linked at my Chat 'n Chew Café Web site:http://www./cafe. Yes, I know this is shameless promotion of my ownWeb activity, but what can I say? Spend time perusing two gooduniversity Web sites that focus on corn production issues. Mine at Purdue:http://www./news/archive.html Roger Elmore’s at Iowa StateUniv: http://www.agronext./corn 在智能手机或平板电脑在上安装 GIS 应用程序，用它来标注地块中的问题区域以供将来参考。我在 iPad 里用了一个名为 GISRoam 的应用程序，能够很好地标注问题区域或地块特征。还有一个叫做 iGIS 的应用程序我没有用的足够多，但值得一试。如果你使用iPhone，我建议你考虑一款包含额外电池的手机壳，巡田时能支持更长时间的 GIS 程序使用。 利用上一年的产量地图，可以帮助你锁定地块中的一些特定的点，帮助寻找YIFs。在这些特定的区域采集土样检测。有意识地以这些区域为目标在生长季巡田。 你是否有航拍的权限？仅凭航拍图像本身很难找到照片中田间有差异的真实原因。你需要借助图像实地找到田间的问题点。 本次讨论的基础是，在生长季多下地，尽早在证据还存在，还能帮助诊断的时候找到这些问题区域，了解到底发生了什么。 Did your wife buy you asmartphone or tablet for your birthday with 3G cellular connectivity? Install aGIS app on it and use the thing to map problem areas in the field for futurereference. I have used an app called GISRoam with my Apple iPad to map problemareas or field features with reasonably good success. There’s another appcalled iGIS that I have not used enough to comment on, but it’s worth checkingout. If you use your iPhone, I would recommend considering an after-marketphone case that contains an additional battery to provide you with more hoursof GIS field scouting. Take advantage of previousyear’s yield maps to physically direct you to specific spots in a field tocontinue your hunt for YIFs. Target those field areas for specific soilsampling. Target those areas to intentionally scout the following crop season. Do you have access to aerialimagery during the growing season? Recognize that aerial imagery by itselfoften cannot identify the cause of visual differences in a field. That isusually your job using the imagery to guide you to spots in the field. The bottom line with thisdiscussion is… Get out into your fields during the growing season, identifyproblem areas early while the evidence is still there to aid diagnostics, andfigure out what’s going on with your crops! 需要考虑的关键因素 Key factors to consider 尽管我在这篇论文的前面暗示过，不要盲目相信没去过你农场的“专家”，但在确定重要的YIF时我可以提供一些关键因素供你考虑。 Even though I hinted earlierin this treatise that you should not blindly believe any “expert” who has notbeen on your farm, here are a few key factors I can offer to you for yourconsideration as you go about the business of identifying the important YIFsfor your farm. Because I am “Iowa-challenged”, these factors will by necessitybe influenced by my experiences with growing good corn in Indiana. 田间排水 Field drainage 在我所在的东部玉米带地区，排水不良的土壤由于对根和植物发育的影响，是玉米苗齐苗壮的常年挑战。农田排水（地下管道排水或地表排水）的充分性，极大地影响着玉米是能多打 200 多蒲式耳的产量，还是会绝收（积水被淹），或者介于两者之间。 改善地下管道排水或地表排水可以降低积水、土壤潮湿、因反硝化作用的土壤氮素流失以及耕作和其他田间设备造成土壤压实的风险。降低这些风险可以使玉米作物的根系发育和苗期群体建立更加成功，从而使作物能够更好地承受生长季后期的压力。 In my area of the easternCorn Belt, naturally poorly-drained soils constitute a major perennialchallenge to establishing vigorous stands of corn by virtue of their effects onthe success and uniformity of rooting and plant development. The adequacy offield drainage (tile or surface) greatly influences whether corn will produce200-plus yields or nothing (ponded out) or somewhere in between. By improving tile or surfacedrainage in a field, you can reduce the risks of ponding or soggy soils, lossof soil nitrate by denitrification, and soil compaction by tillage and otherfield equipment. Reducing these risks enables more successful root developmentand stand establishment of the corn crop, which in turn will enable the crop tobetter tolerate stresses later in the growing season. 灌溉补充水份 Supplemental water 东部玉米带的一些土壤遇到了相反的问题，当降雨量不足时土壤就容易过早变干。这类农田通常会采用地上灌溉（时针式、喷枪式、行式）或从地下排水管道中抽水来补充水。无论是哪种选择都要根据作物需水情况和土壤可用的水分情况来做灌溉决策（Joern&Hess，2010）。中央灌溉系统的设备维护和正确运行对优化灌溉成本和提高种植效益至关重要。 Some soils in the easternCorn Belt suffer from the opposite problem of drying out too easily whenrainfall is inadequate. Obviously, fields with those soils will usually respondto supplemental water provided by above-ground irrigation(center pivots, shotguns,rows) or below-ground supplementation by virtue of pumping water back into tiledrains or drainage ditches. Either choice requires informed decision-makingrelative to irrigation scheduling based on crop demand and soil wateravailability (Joern & Hess, 2010). Maintenance and proper operation ofcenter pivot irrigation systems is crucial to optimize efficiency in terms ofirrigation costs and crop benefit. 品种选择 Hybrid selection 我们大多数人在选择适合的品种上花的时间太少。看看任何包含多个市面”好”品种的测试试验，你会很容易发现最高和最低产量的品种会有50-100蒲式耳的产量差距。注意这种差距的前提还是每个进入试验的品种都是市面的“好”品种。 选种的关键难点是要识别出既有产量潜力而且还能耐受各种逆境的品种（Nielsen，2010）。最佳方法是评估一个品种在多个地点的表现。各个大学的试验会有一定帮助（爱荷华州州立大学，2011年；Devillez，2011年）。如果你看的是种子公司自己的试验结果，要注意他们的品种试验中通常只包含了少数几个外部竞争品种。 要认识到没有品种能在所有测试中都获胜。寻找在试验中产量稳定，不论种在哪产量都不低于最高产量90%的品种。例如，如果某一试验中最高产量是230 bpa，那么在同一试验中寻找产量至少207 bpa（230 x 0.90）的品种。这听起来可能不难，但你会惊讶地发现，在多个地点进行评估时很少有品种能达到这一目标。 一旦根据产量表现的稳定性确定了一些有潜力的品种，然后再集中精力考察其他重要的性状，比如对你所在地区重要病害的抗性。 Most of us spend too littletime evaluating the documented performance of potential hybrids for use in ouroperations. Look at any hybrid trial that includes “good” hybrids from a rangeof seed companies and you will easily see a 50 to 100 bushel range in yieldbetween the top and bottom of the trial. Mind you, this spread from high to lowoccurs in variety trials where supposedly every hybrid entered into the trialis a “good” hybrid. I doubt that seed companies enter “bad” hybrids on purpose. The key challenge is toidentify hybrids that not only have good yield potential, but that alsotolerate a wide range of growing conditions (Nielsen, 2010). The best way toaccomplish this is to evaluate hybrid performance across a lot of locations.University trials are good for this exercise (Iowa State Univ, 2011; Devillez,2011). If you use seed company trials, be aware that often there are fewcompetitor hybrids included in variety trial results. Recognize that no hybrid winsevery trial in which it is entered. Look for hybrids that consistently yield noless than about 90% of the highest yield in the trial no matter where they aregrown. For example, if the top hybrid in a particular trial yielded 230 bpa,then look for hybrids in the same trial that yield at least 207 bpa (230 x0.90). That may not sound like much of a challenge, but you will be surprisedhow few hybrids will meet that goal when evaluated over a lot of locations. Once you’ve identified somepromising hybrids based on their consistency of performance, then concentrateon other important traits like resistance to important diseases in your area ofthe state. 免耕情况下管理播种障碍 Manage trash in no-till 如果玉米要在排水不良的土壤上免耕种植，你只需努力管理好地表的“障碍”，使地表土壤干燥/变暖，有利于播种机有效的进地作业，并改善作物出苗状况，建立好的苗期群体。 为了在无法控制住冬季一年生杂草或覆盖作物的长势前把它们处理掉，可使用播种机上的清行装置清理种子播种沟区域的“障碍”。避免在“湿侧”种植，尽量减少播种沟的侧壁压实或顶部压实的风险。 尽量使耕作时的行进路径最少，考虑免耕，条带耕作。要记住，即使免耕或条带耕作也不能完全避免土壤压实。 If you no-till corn on soilsthat are poorly drained, then you simply must strive to manage surface “trash”to enable drying/ warming of surface soils, facilitate effective planteroperation, and improve crop emergence / stand establishment. Aim to burn-down winterannual weeds or cover crops before their growth becomes unmanageable. Userow-cleaners on the planter units to remove a narrow band of “trash” from theseed furrow area. Avoid planting “on the wet side” in order to minimize therisk of furrow sidewall compaction or topside compaction. Minimize the number oftillage trips, consider strip-till or no-till systems. Remember, though, thatno-till or strip-till is not immune to the risk of soil compaction. 玉米连作还是轮作？ Continuous corn or not? 坦率地讲，连作玉米的产量不如轮作玉米。在在许多州做过的长期轮作试验都证明了这点。种完玉米之后的免耕玉米上最优可能出现产量降低。那些据说能很好地种植连作玉米的种植者往往非常仔细的对前茬玉米的秸秆进行了处理。 玉米秸秆延迟了土壤的干燥/升温，从而延迟了下茬作物的出苗和生长。玉米秸秆（包括旧根）经常干扰播种机的操作，导致种子深度差/不均匀或种子与土壤接触不良，从而导致下茬作物出苗延迟或不均匀。在下茬作物生长季的早期上茬玉米秸秆的分解会将土壤中的氮绑定住，可延缓玉米生长发育，直到根系发育达到临界质量。玉米秸秆能截留土壤中施用的除草剂，降低杂草防治效果。最后，玉米秸秆含有灰斑病或内州枯萎病等重要病害的病原菌。不管你怎么看，玉米连作制度都充满了挑战。 Frankly, continuous cornsimply does not yield as well as rotation corn. Numerous long-term rotationtrials have documented this across a number of states. The yield drag isespecially likely for no-till corn after corn. Folks who claim to do well withcontinuous corn are often fairly aggressive with their management of the stoverfrom the previous crop. Corn stover delays the drying/ warming of the soil and thus delays crop emergence and development. Cornstover (including old root balls) often interferes with planter operation,causing poor / uneven seed depth or seed-2-soil contact and thus causes delayedor uneven crop emergence. Decomposing corn stover immobilizes soil nitrogen earlyin the season and can retard corn growth and development early in the seasonuntil root development reaches a critical mass. Corn stover can interceptsoil-applied herbicide and reduce the effectiveness of weed control. Finally, cornstover harbors inoculum of important diseases like gray leaf spot or Goss’wilt. Any way you look at it, a continuous corn cropping system is fraught withchallenges. 是否使用种肥（起始肥料）？ Starter fertilizer or not? 种肥，尤其是氮肥，对于东部玉米带实现玉米产量的最大化非常重要。我提供以下解答，您来决定是否是类似的情况。 背景：玉米幼苗大概在 V3 发育阶段（有三片叶有明显的叶领）之前严重依赖籽粒中储备的营养。从这一时期开始，幼苗开始逐步“断奶”，从依靠籽粒中的营养转变为依靠节根系统提供营养。 如果到这一时期之前的幼苗都很健壮，那么向依赖节根的营养过渡将顺利进行，幼苗会充满活力的生长，能够很好地承受未来的逆境压力。 然而，如果在出苗和成苗建立这期间的环境条件持续不利，那么节根发育可能会阻，幼苗将难以“断绝”自己的籽粒储备营养。因此这些幼苗将出现“停滞”，生长将变得不协调，会由浅绿色变为黄色，成苗后将很难充满活力，整齐一致。这样的玉米群体很可能在余下生长季中的逆境中继续挣扎。 在上述第二种情况下，一个好的 2 x 2（离种子一侧及下方各 2 英寸（5厘米））种肥施用计划能帮助幼苗更好的完成向依赖节根的营养过渡。在东部玉米带的经验表明，起始肥料中的氮肥是最主要的营养素，起始氮的比率应不低于每英亩 20 至 30 磅的实际氮；也许比免耕玉米施氮的价格要高。 Starter fertilizer,especially nitrogen, is important for maximizing corn yields in the easternCorn Belt. I offer the following explanation and leave it to you to decidewhether your situation is similar. A little background: Youngcorn plants depend heavily on stored kernel reserves until roughly the V3 stageof development (three leaves with visible leaf collars). At that point, theplants begin to “wean” themselves from dependence on the stored kernel reserves(which are playing out) to dependence on the developing nodal root system. If life up to that point hasbeen hunky-dory, the transition to dependence on the nodal roots will gosmoothly and the crop will continue to develop into a vigorous and uniformstand that will tolerate future stresses nicely. However, if conditions havebeen challenging during emergence and early stand establishment, then nodalroot development has probably been stunted and the young plants will struggleto “wean” themselves from the kernel reserves. Consequently, the plants willappear to “stall out”, their development will become uneven, they will turn lightgreen to yellow, and the resulting stand will not be as vigorous and uniform asyou want. Such a stand of corn will likely continue to struggle the remainderof the season. It is the latter situationwherein a robust 2x2 starter fertilizer program will aid the young plants asthey struggle in the transition to dependence on nodal roots. Our experience inthe eastern Corn Belt suggests that starter nitrogen is the primary importantnutrient and starter N rates should be no less than 20 to 30 lbs actual N peracre; perhaps higher than that for no-till continuous corn. 氮肥管理 Nitrogen management 东部玉米带的氮肥管理具非常有挑战，因为土壤排水不良，降雨量充足，而且反硝化或淋失造成氮损失的风险，因此产量往往低于预期。因为生长季土壤氮含量不足，导致种植者的收入较低。或者种植者有时会施用超过作物需求的氮来减轻氮流失的后果，也投入了更高的费用。以提高玉米氮肥的有效使用为目标的最佳管理实践已得到充分验证(Camberato et al., 2011; Sawyer, 2011)，包括避免秋季施用氮肥，避免在地表施用没有与土壤混合的尿素基氮肥，在可行的情况下使用侧施氮肥的方案。这些做法，加上强有力的种肥施用计划，将有助于减少土壤氮的流失，并最大限度地提高施用每磅氮肥带来的产量。 Nitrogen management in theeastern Corn Belt is challenging because of our poorly drained soils, amplerainfall, and the risk of N loss by either denitrification or leaching.Consequently, yields are often lower than desired because of inadequate levelsof soil N during the growing season, resulting in lower grain income for thegrower. Alternatively, growers sometimes apply more N than the crop requires inan effort to mitigate the consequences of excessive N loss on the crop and,thus, incur higher crop production expenses. Best management practicesthat target the efficient use of nitrogen fertilizers in corn are welldocumented (Camberato et al., 2011; Sawyer, 2011) and include avoiding fall Napplications, avoiding surface application of urea-based fertilizers withoutincorporation, and adopting sidedress N application programs where practical.These practices, plus the implementation of a robust starter fertilizerprogram, will help reduce the loss of soil N and maximize the bushels producedper pound of N fertilizer applied. 病害管理 Disease management 夏季，东部玉米带典型的温暖潮湿条件有助于几种重要的玉米叶部真菌病害的发生，包括灰斑病和北部玉米叶枯病。内州枯萎病是一种潜在的严重细菌性疾病，近年来已“迁移”到印第安纳州，对东部玉米带的种植者来说是一个新的挑战。这些叶部玉米病害很容易使玉米产量下降20%或更多。 有效管理这些重要玉米病害的最佳管理实践已得到充分验证（Wise；2010a、2010b、2011），包括： ·· 选择抗性品种. ·· 避免玉米连作 ·· 避免免耕种植系统 ·· 有效使用叶面杀菌剂（内州萎蔫病除外） Warm, humid conditionstypical of the eastern Corn Belt during the summer months are conducive for thedevelopment of several important foliar fungal corn diseases, including grayleaf spot and northern corn leaf blight. Goss’s Wilt, a potentially severebacterial disease, has “migrated” into Indiana in recent years and represents anew challenge for growers in the eastern Corn Belt. Yield losses from thesefoliar corn diseases can easily decrease corn grain yields by 20% or more. Best management practicesthat target efficient management of these important corn diseases are welldocumented (Wise; 2010a, 2010b, 2011) and include: ·· Hybrid selection forgood disease resistance characteristics. ·· Avoiding continuouscorn cropping systems. ·· Avoiding no-tillcropping systems. ·· Responsible use offoliar fungicides (except for Goss’s Wilt) 记住，种好玉米不是高深的“火箭科学” Remember, it ain’t rocketscience! 显然，在这点上，实现更高、更稳定的产量并不需要“火箭科学”。相反，我们谈论的是许多常识性的农艺技术原理，它们共同作用，将每年发生的常见逆境压力降至最低，并使作物能够更好地承受无法控制的气候逆境压力。本文中未讨论的其他农艺实践包括一个完整的杂草控制方案，该计划侧重于长效残留除草剂的使用，以及在杂草很小时进行治理的理念。 努力找到你农场中最重要的产量限制因素。这需要具备良好的作物巡田检测技能和对农艺技术原理的充分理解。然后与你的作物顾问一起，努力确定并实施针对这些产量限制因素的农艺管理实践。 It should be obvious at thispoint that achieving higher, more consistent yields does not require “rocketscience”.Rather, we’re talking about a lot of common sense agronomic principlesthat work together to minimize the usual crop stresses that occur every yearand allow the crop to better tolerate uncontrollable weather stresses. Otheragronomic practices not discussed in this presentation include a sound weedcontrol program that focuses on the use of residual herbicides and an attitudethat you will aim to kill weeds when they are small. Make the effort to identifythose yield limiting factors that are most important for your specific farmingoperation. This requires good crop detective skills and a sound understandingof agronomic principles. Together with your crop advisor(s), work towardidentifying and implementing good agronomic management practices that targetthose yield limiting factors. |
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