Corn Silage (Continued from Page CIO) ing date in Lancaster county, Pen nsylvania, com silage planted after harvest of barley also averaged 11 tons per acre. Both studies indicate that com silage can produce rea sonable and profitable forage yields in many areas, even when planted in late June. Soil Fertility Program Nutrient removal rates by com for silage are higher than those by com for grain and by most other commonly grown crops (Table 1). Consequently, on soils with low to-optimum soil-test levels, fertil izer recommendations for com grown for silage are 20, 30, and 115 Ib/A higher for N, P 2 0 3 , and K 2 O, respectively, than for com for grain with comparable yields. Because of these higher nutrient requirements, fertility programs can be expensive and monitoring of soil nutrient levels by regular soil testing is critical. The higher nutrient recommendations are made to replace nutrients removed, not because the crop will respond to higher fertilizer appli cations. Where the use of a com crop is uncertain (grain or silage), lower com for grain nutrient recommendations will suffice, provided soil nutrient levels are monitored in the future. Table 1. Plant nutrients contained in a crop with 150-bushel com grain per acre (25-ton silage). Nutrient Grain Stover Total N 115 55 170 P 28 7 35 K 35 140 175 Ca 1 34 35 : *^ =s R)SCO rHI-Flo Water H Filters s • Clear Bowl For Good Visibility ! When Filter Needs To Be Cleaned I | • Reusable Polyester Filter - 100 | Micron ‘ii • Clear Bowl Easily Removed For ™ Cleaning (No Tools Required) PLUMBING • % ” Thru 10” PVC Pipe And Full Line Of Fittings, Valves & Fasteners * Electric Water Solenoid Valves * High Pressure Washers * Galvanized Pipe And Fittings Mg 10 30 40 S 11 9 20 Zn 0.17 0.17 0.3 Biibtf tnd Olson, 1968 Since com silage is usually pro duced on farms with livestock, soils planted to com for silage often receive manure applications and are rotated with forage legume crops. This frequently results in optimum-to-high soil nutrient levels and relatively low fertilizer requirements. The key to develop ing plant nutrient recommenda tions is to soil test and to account for manure applications and for previous crops in the rotation. This strategy will minimize fertility program costs and maintain the potential for high yields. Weed And Insect Management Control strategies for weeds and insects in com for silage are simi lar to those used in com for grain. These strategies are discussed in detail in “The Penn State Agro nomy Guide.” Silage yields are more sensitive than grain yields to insects that reduce stands because com plants have difficulty com pensating completely for missing plants. Com for silage, because of its earlier harvest, is impacted less by insects and diseases that prom ote lodging, such as European com borer, com rootworms, and stalk rot. Late-season scouting can iden tify fields with these problems while they can still be harvested for silage. Harvest Considerations One of the most important fac tors influencing com silage quality is stage of growth or moisture con tent at time of harvest. Ideally, com silage should be harvested at DRIP NOZZLE DRIP COOL SYSTEMS ” Lactating Sows • Gestating Sows • Boars SPRAY COOL SYSTEMS • Finishing Hogs the moisture content appropriate for the type of silo used. Recom mended moisture contents are 65-70 percent for horizontal silos, 63-68 percent for conventional tower silos, and 55-60 percent for limited-oxygen silos. Between the moisture levels of 60 and 70 per cent, crop quality and dry matter yield are maximized and losses during feeding, storage, and harvesting are minimized (Table 2). Table 2. Expected dry matter losses of whole-plant corn silage harvested at different moisture contents. Moisture Com that is ensiled too wet wiu ferment poorly and lose nutrients by seepage, which also has poten tial to damage the silo. Silage that is too dry will result in air pockets that prevent anaerobic fermenta tion and allow development of molds. In dry, overmature, com silage, the stover portion of the plant is less digestible and contains lower amounts of vitamins A and E than com ensiled at the recom mended moisture levels. In addi tion, the overmature kernels become harder and less digestible. Silage moisture at harvest is not difficult to determine and should be monitored, if possible, to pre vent harvesting of the crop outside of the desired moisture range. A commercial forage moisture tester or a microwave oven can be used to determine the moisture content fairly rapidly. Moisture content can also be estimated by the stage of kernel development, as characterized by the position of the kernel miik line. The kernel milk line appears as a TWO WAYS For INVENTORY^ Harvest Storage Feeding >7O 4.0 13.4 4.0 61-69 5.0 6.3 4.0 <6l 16.2 6.3 4.0 whitish line separating the kernel starch and milk. This appears near early dent stage and moves down the kernel as the grain matures. Data from studies conducted at Penn State indicate silage moisture contents at full dent (all kernels dented), half milk, and black layer stages average 68,61, and S 3 per cent, respectively. These are only estimates, however, and may vary by about plus-or-minus 4 percent, depending on the year and hybrid. Consequently, the moisture con tent should be monitored, if possi ble, to ensure accuracy. As a general rule, harvest should begin at the full dent to one-third milk line stage. This will usually maximize digestible dry matter yields and help to avoid harvest of fields that are overmature. Avoid moisture levels of less than 62 per cent because they may increase the risk of abnormal fermentation, higher dry matter losses, lower energy content from hard grain, and silo fire. When com silage pro vides over 65 percent of the forage dry matter, harvest at the early dent stage should be considered to pro vide more forage fiber and fat solu ble vitamins. A tactic that helps predict harvest date is to chop a sample of plants one to two weeks before the crop is ready. The moisture con tent can be measured then and opti mum harvest date can be pre dicted, using a drying rate of about Required • Reliable Liquid Dispenser VENTILATION • Moisture And Dustproof Controllers, Thermostats, Variable Speeds, Timers * Gravity Inletting Systems Lancaster Farming, Saturday, July 27, 1991-Cl 1 0.5 percentage points per day. Care should also be taken not to chop the com silage too fine. Aver age particle size should range from 3/8 to 3/4 of an inch in length with IS percent of the particles 1 to 1.5 inches in length. Particle size should be monitored during harvesting because it can change as crop moisture content varies. Chopping too fine has been shown to use more fuel in harvesting and to result in a silage which may depress milk fat test values. Once harvesting has begun, fill the silo as rapidly as possible and continue until it is filled. Loads should not stand overnight, because they can heat and spoil. Total 21.4 15.3 26.5 Com is occasionally damaged or killed by frost before it reaches the desired maturity for ensiling. If the frost is early and green leaves remain on the plant, the crop will continue to accumulate dry matter and should be left in the field until it reaches the appropriate moisture content. Plants that are killed and still immature will likely contain too much moisture for immediate ensiling. These plants will dry slowly and dry matter losses will increase as the dead plants drop their leaves in the field. The best option is to leave the crop in the field to dry to an acceptable level, unless it appears dry matter losses are becoming too high or harvest ing losses will increase dramatically. Drought-stressed corn When com is so drought stressed that it may not resume growth, it should be ensiled. Com in this condition usually has few SPRAY NOZZLE DOSMATICPLUS medicator DO9MAIC Accurate at all Flow Rates No Electricity WE SHIP U.P.S. DAILY * Aerotech High Quality Fan And Shutters Frosted corn (Turn to Page Cl 2) y
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