Fertility Requirements For Summer Annuals – by Gerry Davis

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It has been said that sorghums can grow on ground that corn won’t, however meeting fertility needs is as still important with sorghums (sorghum-sudans, forage sorghums and sudan hybrids) as with any crop.

Sorghums will produce twice the forage on an inch of rain or irrigation as will corn, but they do have similar nitrogen needs. Nitrogen needs for sorghums can most easily be expressed as 1 to 1½#’s N/acre per growing day. This separates the multi-cut sorghum-sudans (SS) and sudan hybrids (SH) from the single cut forage sorghums (FS). SS and SH should be spoon-fed due to the luxury feeding of N by these plants. Limit the N to the amount needed between cuttings. Since they are first cut in 45 days after planting and every 30 days thereafter (with adequate sunlight), suggested application rates are 45-50 units and 30-35 units, respectively. These rates of N application are important to prevent nitrate toxicity. Obviously, single-cut FS needs to have the N in place for the whole growing period unless fertigation (fertilizing thru irrigation) is used.

Sorghum, like corn silage removes a huge amount of biomass from the soil which requires the replacement of N, P and K. Unlike GMO corn, however, the sorghum root-mass breaks down readily and returns organic matter more quickly to the soil. See table 1 for nutrient uptakes for various 30% DM forage removal rates.

Summer Annuals Nutrient Requirements
Tons biomass @ 30% DM Nitrogent Ibs/Acre P as P2O5 Ibs/Acre K as K2O Ibs/Acre
10 50 45 80
15 75 65 100
20 100 75 120
25 125 75 140
30 150 75 160

Table 1 (from Purdue Forage Field Guide 2009)

With any fertility recommendation comes the advisory to test the soils and know the cropping history of the field you are planting. This is especially true where residual herbicides have been applied. Manure applications are must also be accounted for and are recommended for only the pre-plant and not the second or third application in SS and SH plantings.

Building A Better Pasture & Hay Fertility Program – by Dennis Brown

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As the title suggests we need to look at our forage fertility as a program.

The definition of a program is “a planned, coordinated group of procedures for a specific purpose.” Our purpose is to get the most kilocalories per acre. This includes forage quality and yield. Producers wonder why does the nutrient levels of their pasture and hay ground appear to be so lacking, when fertilizer is being spread and/or manure is constantly being applied or (deposited) there? This is a common question from those growers who have soil tests pulled on their pasture and hay ground. For the ones that don’t have soil test they are not sure why the yield is not there, why the cows won’t milk, or why the stock just won’t eat the hay or grass as well.

How many producers assume that due to stocking rates they will have adequate fertility because of all the manure being deposited on their pasture and all the money spent on fertilizers on hay acres? And how many livestock producers spend large sums of money to purchase excellent animals and then put them on pastures or feed hay that receive an occasional fertilizer top-dressing, and expect it to suffice for maintaining top herd health and excellent pasture fertility. Cattle will utilize minerals from forages up to 30% more efficiently than free choice fed minerals.

Unfortunately, it seems that so many who have livestock on pasture, incorrectly make this type of assumption. There are those who have successfully accomplished growing grass this way, to a point and, consequently, too many consider that testing pasture and hay fertility levels is completely unnecessary. But there are times and circumstances when a high price must be paid for thinking like that. It can ultimately result in costly losses in terms of plant and animal health, and even needlessly limit potential forage production. Most pasture and hay soils treated this way will never come close to attaining their top production potential, especially the improved forage genetics that Byron provides. The forages are only as good as your soils. Same as your cows are only as good as your feeding program.

Most soils need more than N- P- K. N-P-K should be added in sufficient amounts if required, but not at the expense of neglecting other required nutrients for top performance such as Calcium, Boron, Sulfur, and Zinc. Furthermore, the two nutrients most affected by manure in terms of an increase in soil fertility levels are phosphorous and potassium. Nitrogen is harder to measure because of the leaching effect and microbial tie up in the organic matter of the soil. In other words, two of the three macro nutrients most often supplied as fertilizer are the most likely nutrients to be supplied from manure. The producer needs to be careful not to over apply manures or over apply P and K in any form.

Excess nutrients can have just as a negative affect as a deficeienes of nutrients. Our goal is to have a balance of nutrients in the soil. However, we should keep in mind: because manure that is produced on pastures that are already lacking one or more of these needed nutrient will likely also be short when it comes to supplying those same nutrients. On dairy farms calcium is the #1 nutrient that lacking, this is due to milk has a percentage of calcium per volume and it leaves the farm daily. Such deficiencies occur in far more forage acres than most producers seem to suspect.

Many producers are not comfortable enough to make fertility recommendations with or without without a soil test. Here is a general rule of thumb on making recommendations if you know how much nutrients are removed with each ton of forage. With this knowledge you can recommend enough nutrients to replenish what was removed or the nutrients needed to start a new seeding.

Below are suggested levels on a soil test for optimum forage tonnage and quality. If you do have a soil test you can use these recommendations. Saying this doesn’t make these levels gospel! Soil fertility is just a piece of the puzzle. Mother Nature has a larger hand in forage production than what we do. But if she decides to play nice and have favored on us, these levels will give you the optimum forage. Although if we can keep the fertility levels adequate it will help the forages go through stressful situations and will greatly increase the total persistence of the forage stands.

Fertility Guide
Organic Matter 2-4%
CEC 12-19
pH 6.5-7
P1 (phosphorous) 30 ppm
K (potassium) 200 ppm
S (sulfur) 15 ppm
B (boron) 2 ppm
Zn (zinc) 5 ppm


Base Saturation
K 6-8%
Ca 70%
Mg 20%

The Value of Fall Seedings – by Samuel Fisher

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Late summer and early fall has many advantages over spring for planting forages. Planting at this time of year can spread your risk and you can, at times, depending on weather and latitude harvest quite a bit of high quality forage before winter.

Having plants growing late in the fall gives you the chance to harvest sunlight for more days of the year. This benefits soil life and keeps it active – giving you more and quicker yields in the following spring and beyond. Here are some fall seeding options:

Perennial Pasture

  • Can be seeded after corn except in the most northern areas of the Midwest
  • Less weed pressure than spring seedings
  • Get 2 tons per acre more next year compared with a spring seeding next year
  • Pasture is ready for early grazing next year
  • Better stands than spring seeded stands
  • Overall our experience has been that fall seeded stands outperform spring seedings in yield and density

Alfalfa and Grass Hay/Haylage Mixture

  • Alfalfa has to be seeded 5 weeks before frost to ensure winter survival
  • Fall seeding provides much better broadleaf weed competition than spring sowings. The grass out-compete weeds
  • 2-3 tons per acre more hay next year (at $250 per acre or more)
  • Healthier more active soil compared to spring seedings

Double Cropping with Annuals

  • Great way of extending the growing season with very high quality feed
  • Annual grains and grasses have excellent root structures to recycle nutrients and loosen soil
  • Yields an additional 2-4 tons of dairy quality hay per acre – at a value of $200 per ton or more.

Cover Crops

  • For those who are serious about building soils
  • Allows something green and growing for more days of the year.
  • Cover crops outcompete weeds and can reduce pests and diseases, meaning less pesticide use
  • Helps mellow soils and slowly release nutrients
  • Builds long term yield potential of cash crops

Setting a Drill – by Ernest Weaver

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Calibrating a drill, the only way to know for sure how much of a particular drill will deliver of a particular seed, must seem like too much work. The evidence is that everyone wants a magic chart that will be right for every seed and every drill. Wee, we want one, too! Here are some tips that can speed up the process of accurately putting the right amount of seed in the ground.

Seeds with commonly known bushel weights, like small grains Bushel weights being heavy or light compared to the accepted weights are the biggest chance for error in seeding small grains using the charts on the drill. Tim Huffman and Kurvin Zimmerman use a bushel weight scale (pictured on the right) to ascertain the actual bushel weight Tim Huffman says, “I’ve tried the old way as described In the 2010 Forage Resource Guide, but this works way better.

You first must obtain a bushel weight scale as pictured here. They are available from $40 to $65 on the internet or from the Nasco catalog. Measure the weight of the seed per bushel, say it is wheat, if it is different from the expected (for wheat 60Ibs). So let’s say the actual bushel weight is 57Ibs. Always divide the expected by the actual. So 60/57=1.05. So for every 100 pounds you want to seed, set the drill at 105. If your seed is not listed on the drill’s chart, pick a seed close to the same expected weight (triticale would use the wheat scale).

Grass Seeds not listed on the drill’s seed chart Tall fescues and festuloliums are exactly the same size and rygrasses and meadow fescues are only slightly different and should go in the large seedbox. If the seed chart lists “crested wheatgrass,” and many drills do, use that setting since this grass is exactly the same size and shape as tall fescue. If your chart doesn’t list crested wheatgrass you will be using the wheat setting chart. The setting for wheat at 20Ibs will be approximately the setting for 10Ibs of tall fescue and Festulolium and probably also the starting point for the other larger seeded grass (timothy, bluegrass and orchardgrass are the smaller seeded grasses and probably will be seeded thru the alfalfa box. Remember we said a “starting point” as every drill is different, but try it with a small amount of seed to get started in the right direction. The grass seeds are fluffier and less dense than wheat so this is the reason that the setting is higher for fescue than wheat.