收割玉米的艺术
教育资源
秋天的玉米收获是我一年中最喜欢的季节之一. The acres of young seedlings have grown tall and are now reaching the optimum point of harvest as either forage for livestock or grain for a nearly unlimited list of uses.
玉米是一种有趣的植物，因为它不存在于“野外”.” Corn is a 100% man-made plant and its breeding stretches back over 8000 years. From its humble beginnings, corn has evolved into the world’s leading crop for two reasons. 第一个, corn produces more total nutrients per acre than any other crop and second, 玉米很容易机械化.
As we enter into the harvest season and examine the methods and machinery used to harvest corn, we note that how the corn is to be used directly impacts how it is harvested. 正如我前面提到的，玉米可以用作饲料作物. Corn silage can be utilized by ruminants, namely cattle as a source of energy and fiber.
Corn silage is made by chopping the entire plant into pieces approximately 3/8” long. This is accomplished by using a forage harvester, commonly called a “chopper” in farming circles. Choppers can be either pulled by a tractor as seen in the photo or be self-propelled. Many modern choppers have kernel processors that crush the corn grain for more efficient use by the animal. 在这种情况下，颗粒长度通常增加到3 / 4英寸.
图片来源: Tim Malin和IH Group在脸谱网上
不管它的推进方式如何, the corn crop is clipped a few inches above the ground and fed into a spool of blades (knives) capable of making over 200 cuts per second. The blades clip the incoming corn by using a stationary shear bar that give the blades a scissor action, 提供清洁, 低功耗减少.
图片来源: Tim Malin和IH Group在脸谱网上
The freshly cut silage is placed and packed in a silo where it will undergo a fermentation process that allows the forage to be stored and fed over the course of the next year. 筒仓可以是垂直的塔, and silage can be placed into long plastic bags but the most used method is to pile the silage into horizontal bunkers, where the forage is spread and packed by heavy equipment or large tractors.
图片来源: Dr. 冈萨洛·费雷拉，弗吉尼亚理工大学
Bunkers offer quick feed out that is critical to today’s larger animal feeding operations. 更很少, 玉米可以被加工成“矿渣”,” using the same chopper with a snapper head that plucks the ear off the stalk and processes it as a more energy dense feed.
图片来源: Dr. 冈萨洛·费雷拉，弗吉尼亚理工大学
作为谷物收获的玉米也被折断了茎秆, 但从那时起, 谷物的处理要温和得多. The corn plant is generally drier at harvest and the possibilities of shattered kernels is higher. 不管用什么, 破碎的玉米粒意味着玉米的价值降低, 虽然零破损是不现实的, 将损害降到最低在经济上是有意义的.
图片来源: Tim Malin和IH Group在脸谱网上
Again, the way the corn is to be used has a direct bearing on the machinery used to harvest it. 有些玉米是通过收集整个玉米穗来收获的. Examples of corn harvested in this way include sweet corn (What’s corn on the cob without the cob?)、爆米花和玉米种子.
图片来源: 安德鲁Overbay
Machines that harvest these crops are called pickers and can range from antique tractor mounted units, 从拖拉机牵引的采摘机到大型自走式采摘机.
Even though popcorn and seed corn do not utilize the cob in their final form, 这种方法可以用最温和的方式处理玉米, 同样，因为在这两种情况下，果仁破碎会使收获毫无价值.
玉米种子是一种非常珍贵的作物. 正如我们在本博客开头提到的, corn is an entirely man-made crop and seed corn represents the future of the next crop of corn. 每一种玉米新品种都投入了数亿美元, 所以玉米种子在很多方面都很珍贵.
图片来源: 斯科特·瑞特，弗吉尼亚州乔治国王县的推广代理人
Seed corn production is highly monitored especially in the pollination phase. Corn is de-tasseled to ensure only the intended plant breeding occurs and then the male plants are destroyed. Only the female plants are harvested (male ears are very much larger and are sorted out if harvested) and the ears are de-husked and placed in driers as soon as they reach the seed processing facility.
一旦玉米种子晒干, the ears are shelled and the kernels are bagged or boxed to be ready to go the field next spring.
Finally, when most people think of harvesting corn, the corn combine comes to mind. Combines can be used to harvest other crops like small grains (wheat, barley, rye) or soybeans. The front of the combine that first comes in contact with the crop is called the “header” and corn heads differ from other crops significantly.
玉米头的特点是有鼻子, long pieces of metal or plastic that extend into the crop between the rows. 就像采摘者一样，它的头会咬掉耳朵，把茎和叶子挤出来. Unlike pickers, the ears are directed into a rotor via the combines feeder house. The rotor places the ears against the cage and the other ears and the kernels fall through the holes in the cage while the cobs and other larger pieces of material are chopped and expelled.
图片来源: 斯科特·瑞特，弗吉尼亚州乔治国王县的推广代理人
The kernels and some foreign material run through a shaker and then subjected to blasts of air from a high-speed fan. 震动和空气爆炸有助于进一步“清洁”谷物. The grain is collected in the combine’s large bin until it is unloaded into a truck, 或将货物卸到卡车上的大车, 去当地的谷物升降机或农场的仓库.
从那里, the shelled corn is graded and its use is determined based the absence of foreign material and broken kernels. Those uses can range from animal feed to ethanol to corn syrup for your favorite carbonated beverage to binders to hold medications together.
不管用什么, a dark green field of growing corn is a beautiful sight and the life blood of many of our farms and industries.
作者
安德鲁Overbay, 单位协调员和推广代理, 农业与自然资源, 弗吉尼亚理工大学