—A Valuable Source of Information for Farmers — Andrew Frankenfield, Montgomery County Extension
The Web Soil Survey (WSS) is operated by the USDA Natural Resources Conservation Service and provides free access to the largest natural resource information system in the world. The WSS is a Web application that provides customers (producers, agencies, Technical Service Providers, and others) electronic access to relevant soil and related information needed to make wise land use & management decisions. Users can get information on only what they want by highlighting areas on the map and collect information relevant to their land use concerns.
A farmer can look at cropland by typing in an address and zooming into desired fields. Then outline the fields to create the area of interest (AOI). Once the AOI is defined, next select the “soil map” tab to view the soil types in the field broken down by acres. Next the “soil data explore” tab provides information for the field such as the land classifications, which includes capability class and farmland classification. The “soil data explorer” tab also provides vegetative productivity which includes yields of irrigated and non-irrigated crops. Also, if you are thinking of building a pond it suggests areas where the soils are better suited for ponds to avoid seepage.
Lastly the “shopping cart” tab allows the user to print out a custom report for the area selected. This information can also be saved as a pdf document for referencing at a later time. This is extremely useful information for farmers as they evaluate renting or purchasing farmland or for those who are looking to better manage the land that they currently manage. The Web Soil Survey is available at http://websoilsurvey.nrcs.usda.gov/app/HomePage.htm
Thursday, July 29, 2010
Thursday, July 22, 2010
Spring Canola: Emerging Biofuel Feedstock
— Greg Roth, Grain Crop Management and Joel Hunter, Crawford County Extension
Spring canola is another crop in our Bioenergy Crop Demonstration this year. Spring canola is a widely grown oil seed in North Dakota and the Canadian prairies. Spring canola is a cool season brassica crop that produces an oilseed with approximately 40% oil. Canola was derived from rapeseed through conventional breeding practices that have led to a food grade oilseed with reduced levels of glucosinolates (which contribute to the sharp taste in mustard) and erucic acid (a fatty acid not essential for human growth). In 1985 the U.S. Food and Drug Administration (FDA) declared canola “Generally Recognized as Safe” (GRAS), leading to a significant growth in consumption of canola oil and production of the crop in this country.
We began working with spring canola in 2007 to develop some basic production recommendations for Pennsylvania and explore the fit in our cropping rotations. Canola is spring seeded at a rate of 5 pounds per acre and managed similarly to oats. Recommended nitrogen rates are about 2 LB. N per bushel and yields are often in the 40-50 bushel/acre range. For a 40-bushel-per-acre crop with optimum P and K levels, the N-P2O5-K2O recommendations would be 80-30-20. A wide range of spring canola varieties are available, from conventional, conventional/Clearfield, and transgenic glyphosate and glufosinate tolerant lines.
Canola markets are limited but are growing with interest in homegrown biofuel feedstocks. Canola is the oilseed of choice for straight vegetable oil (SVO) feedstock for tractors. Our Farm Operations department at Penn State, led by Glen Cauffman and Don Rill, have been conducting a demonstration of SVO tractors and this has led them to increasing their canola production. They have generally been achieving yields of about 50 bushels per acre, or about 100 gallons of canola oil per acre. This year, we have a 40 acre field in production that Don is managing to help supply the feedstock for the tractor study.
Canola has some potential to fit in to rotations as a spring crop substitute for oats or soybeans. With a similar production cost to oats and a grain value of about $7.00+ per bushel, net returns should be competitive with oats plus straw. Canola straw is generally not harvested, so there would be less labor with this crop. Canola production costs are higher than soybean production due to its N requirement and returns are lower, making soybeans often a more profitable crop than canola. Because of its early August harvest, there is more potential for seeding cover crops following canola than full season crops. We currently have a new spring canola factsheet in publication that will have more details. It will be available next month.
To find out more about canola and other renewable and alternative energy subjects, plan on visiting Ag Progress Days on August 17–19 and be sure to visit: “Ask the Expert” — in the College building, “Renewable and Alternative Energy” in the energy tent, and “Biofuels and Biodiesel” in the crops building.
Spring canola is another crop in our Bioenergy Crop Demonstration this year. Spring canola is a widely grown oil seed in North Dakota and the Canadian prairies. Spring canola is a cool season brassica crop that produces an oilseed with approximately 40% oil. Canola was derived from rapeseed through conventional breeding practices that have led to a food grade oilseed with reduced levels of glucosinolates (which contribute to the sharp taste in mustard) and erucic acid (a fatty acid not essential for human growth). In 1985 the U.S. Food and Drug Administration (FDA) declared canola “Generally Recognized as Safe” (GRAS), leading to a significant growth in consumption of canola oil and production of the crop in this country.
We began working with spring canola in 2007 to develop some basic production recommendations for Pennsylvania and explore the fit in our cropping rotations. Canola is spring seeded at a rate of 5 pounds per acre and managed similarly to oats. Recommended nitrogen rates are about 2 LB. N per bushel and yields are often in the 40-50 bushel/acre range. For a 40-bushel-per-acre crop with optimum P and K levels, the N-P2O5-K2O recommendations would be 80-30-20. A wide range of spring canola varieties are available, from conventional, conventional/Clearfield, and transgenic glyphosate and glufosinate tolerant lines.
Canola markets are limited but are growing with interest in homegrown biofuel feedstocks. Canola is the oilseed of choice for straight vegetable oil (SVO) feedstock for tractors. Our Farm Operations department at Penn State, led by Glen Cauffman and Don Rill, have been conducting a demonstration of SVO tractors and this has led them to increasing their canola production. They have generally been achieving yields of about 50 bushels per acre, or about 100 gallons of canola oil per acre. This year, we have a 40 acre field in production that Don is managing to help supply the feedstock for the tractor study.
Canola has some potential to fit in to rotations as a spring crop substitute for oats or soybeans. With a similar production cost to oats and a grain value of about $7.00+ per bushel, net returns should be competitive with oats plus straw. Canola straw is generally not harvested, so there would be less labor with this crop. Canola production costs are higher than soybean production due to its N requirement and returns are lower, making soybeans often a more profitable crop than canola. Because of its early August harvest, there is more potential for seeding cover crops following canola than full season crops. We currently have a new spring canola factsheet in publication that will have more details. It will be available next month.
To find out more about canola and other renewable and alternative energy subjects, plan on visiting Ag Progress Days on August 17–19 and be sure to visit: “Ask the Expert” — in the College building, “Renewable and Alternative Energy” in the energy tent, and “Biofuels and Biodiesel” in the crops building.
Sunday, June 27, 2010
Rodale hosts the Pennsylvania Women in Agriculture Network
The PA Women in Ag Network (PA WaGn) and the Rodale Institute partnered on June 4th to showcase Rodale’s latest research in organics and provide a great opportunity for farmer-to- farmer networking. Are you interested in measuring your soil organic matter instantly in the field? Are you tired of throwing away plastic mulch? Read on.
Ann Stone from PA WaGn and Jeff Moyer from Rodale kicked off the day, welcoming us to Rodale. Then we were off to a tour of the farm led by researchers Jeff Moyer, Rita Seidel, Alison Grantham and their team. After a fabulous lunch, we spoke with Temra Costa, author of “Farmer Jane,” and learned about certification from Pennsylvania Certified Organic, and opportunities available for farmers from Natural Resources and Conservation Service. Here are a few highlights.
Alternatives to Black Plastic – Many of us use black plastic mulch. The alternative in a weedy field can be days lost to cultivation and hoeing. And boy do those tomatoes and melons grow faster and produce earlier with their roots warmed under plastic. But in the fall when it is time to rip up the plastic, you like me, might not be as cheerful. Plastic is expensive and time consuming to rip up, and the bill at the landfill is expensive. “Not only do none of us want to see our precious resources buried in the landfill, research shows that we lose 30-40% of our agricultural chemicals to runoff in fields with black plastic compared to un-mulched fields,” says researcher Alison Grantham.
Rodale researchers are hoping that rolled cover crop mulches can provide a viable alternative to plastic mulch. Grantham and her team planted vetch, rye and vetch/rye cover crops last fall. In early June they rolled or flail mowed all three types of cover crops. Tomatoes will be planted directly into the rolled or mowed cover crop by hand. The cover crop will act as a mulch, suppressing weeds and keeping the ground moist. They will compare the yield, and quality of the fruit to other plots where the tomatoes are planted into regular black plastic. Think of it this way. Instead of tilling up the ground in spring, and going to all the trouble of hauling in tons of straw to mulch your tomatoes or other crops, you could grow your mulch in the field. There is little question that growing your own mulch can work. In fact, I visited a farmer yesterday who does just that. But the question remains whether the yield you may lose to colder soils is made up with fewer costs and less labor.
Can I track my soil carbon? First, why would you want to track soil carbon? You might have heard of carbon sequestration. We know that carbon in the atmosphere is contributing to global warming. Sequestration is a way to store carbon – in the soil, in trees, in the ocean, where it can’t cause problems in the atmosphere. As we acknowledge that it is important to keep carbon out of the atmosphere, there is increasing talk of paying farmers “credits” for practices that keep carbon in the soil (organic matter is primarily carbon). So far farmers would be paid for doing a number of practices scientists have found are good at storing soil carbon. But we know that every farm is different, and the science showing which practices work is far from complete. If we can easily track how carbon changes on each of your farms, and see where and after which practices it changes, it will give us much better information about what practices really store carbon in the soil. Instead of paying for what we think works, we would be paying for what really works. Since farmers are great innovators and know their farms the best, tracking soil carbon in real time, with easy measures could be immensely effective.
At Rodale, researcher Elaine Viglione (right) is working to develop a mobile lab that would measure soil carbon right there, in the field. The lab is simple – a cardboard box holds a plastic tube that you lay a core of soil in. Elaine runs a hand-held tool called a spectrometer to measure the visable, near-infared and mid-infared reflectance (color) of the soil core. Remember the colors we see are the distribution and wave length of light reflected off a surface interpreted by the light receptors in our eyes. This machine is acting like a more sensitive version of our eyes “reading” the light reflected off the soil in a core from your field. Elaine will be comparing the readings from this machine to the numbers from traditional soil carbon analysis to see if the tool can give us better and quicker data.
Keep an eye out. It may not be too many years before you are able to measure your contribution to slowing global warming with this quick, effective technology.
What do women have to do with how America eats? The new book “Farmer Jane,” profiles women farmers, educators, advocates and chefs who are changing the way we eat. We were lucky enough to speak with Temra Costa, the book’s author. A few years ago Temra looked around the table in the non-profit/advocacy end of sustainable food systems and realized, “Hmm, we are mostly women.” Not all the movers and shakers in the sustainable food and farming movement are women, but many are. When Temra looked closer, she realized that of the top 15 national nonprofits focusing on sustainable agriculture issues, women comprise 62 percent of the employees and 60 percent of the executive directors. As mothers of children, nurturers of health and the ones in control of 85 percent of household budgets, women have the largest impact and concern when it comes to what they feed themselves and their families. Just look at your CSA members – most are women. On the farm, women are one of the fastest-growing demographics to own and operate farms in the United States and they are tending toward diversified, direct-marketed foods that create relationships with eaters.
Temra highlights many women in the sustainable food and farming movement in her book. Of course, there are many more (and men as well as women), Temra admits, but she hopes the few she was able to describe will be an inspiration.
Ann Stone from PA WaGn and Jeff Moyer from Rodale kicked off the day, welcoming us to Rodale. Then we were off to a tour of the farm led by researchers Jeff Moyer, Rita Seidel, Alison Grantham and their team. After a fabulous lunch, we spoke with Temra Costa, author of “Farmer Jane,” and learned about certification from Pennsylvania Certified Organic, and opportunities available for farmers from Natural Resources and Conservation Service. Here are a few highlights.
Alternatives to Black Plastic – Many of us use black plastic mulch. The alternative in a weedy field can be days lost to cultivation and hoeing. And boy do those tomatoes and melons grow faster and produce earlier with their roots warmed under plastic. But in the fall when it is time to rip up the plastic, you like me, might not be as cheerful. Plastic is expensive and time consuming to rip up, and the bill at the landfill is expensive. “Not only do none of us want to see our precious resources buried in the landfill, research shows that we lose 30-40% of our agricultural chemicals to runoff in fields with black plastic compared to un-mulched fields,” says researcher Alison Grantham.
Rodale researchers are hoping that rolled cover crop mulches can provide a viable alternative to plastic mulch. Grantham and her team planted vetch, rye and vetch/rye cover crops last fall. In early June they rolled or flail mowed all three types of cover crops. Tomatoes will be planted directly into the rolled or mowed cover crop by hand. The cover crop will act as a mulch, suppressing weeds and keeping the ground moist. They will compare the yield, and quality of the fruit to other plots where the tomatoes are planted into regular black plastic. Think of it this way. Instead of tilling up the ground in spring, and going to all the trouble of hauling in tons of straw to mulch your tomatoes or other crops, you could grow your mulch in the field. There is little question that growing your own mulch can work. In fact, I visited a farmer yesterday who does just that. But the question remains whether the yield you may lose to colder soils is made up with fewer costs and less labor.
Can I track my soil carbon? First, why would you want to track soil carbon? You might have heard of carbon sequestration. We know that carbon in the atmosphere is contributing to global warming. Sequestration is a way to store carbon – in the soil, in trees, in the ocean, where it can’t cause problems in the atmosphere. As we acknowledge that it is important to keep carbon out of the atmosphere, there is increasing talk of paying farmers “credits” for practices that keep carbon in the soil (organic matter is primarily carbon). So far farmers would be paid for doing a number of practices scientists have found are good at storing soil carbon. But we know that every farm is different, and the science showing which practices work is far from complete. If we can easily track how carbon changes on each of your farms, and see where and after which practices it changes, it will give us much better information about what practices really store carbon in the soil. Instead of paying for what we think works, we would be paying for what really works. Since farmers are great innovators and know their farms the best, tracking soil carbon in real time, with easy measures could be immensely effective.
At Rodale, researcher Elaine Viglione (right) is working to develop a mobile lab that would measure soil carbon right there, in the field. The lab is simple – a cardboard box holds a plastic tube that you lay a core of soil in. Elaine runs a hand-held tool called a spectrometer to measure the visable, near-infared and mid-infared reflectance (color) of the soil core. Remember the colors we see are the distribution and wave length of light reflected off a surface interpreted by the light receptors in our eyes. This machine is acting like a more sensitive version of our eyes “reading” the light reflected off the soil in a core from your field. Elaine will be comparing the readings from this machine to the numbers from traditional soil carbon analysis to see if the tool can give us better and quicker data.
Keep an eye out. It may not be too many years before you are able to measure your contribution to slowing global warming with this quick, effective technology.
What do women have to do with how America eats? The new book “Farmer Jane,” profiles women farmers, educators, advocates and chefs who are changing the way we eat. We were lucky enough to speak with Temra Costa, the book’s author. A few years ago Temra looked around the table in the non-profit/advocacy end of sustainable food systems and realized, “Hmm, we are mostly women.” Not all the movers and shakers in the sustainable food and farming movement are women, but many are. When Temra looked closer, she realized that of the top 15 national nonprofits focusing on sustainable agriculture issues, women comprise 62 percent of the employees and 60 percent of the executive directors. As mothers of children, nurturers of health and the ones in control of 85 percent of household budgets, women have the largest impact and concern when it comes to what they feed themselves and their families. Just look at your CSA members – most are women. On the farm, women are one of the fastest-growing demographics to own and operate farms in the United States and they are tending toward diversified, direct-marketed foods that create relationships with eaters.
Temra highlights many women in the sustainable food and farming movement in her book. Of course, there are many more (and men as well as women), Temra admits, but she hopes the few she was able to describe will be an inspiration.
Thursday, June 17, 2010
Spinach Leaf Miner
Spinach leafminer seems to be more prominent than usual this spring in Southeastern Pennsylvania. After receiving a call, I started asking growers and many of them have seen it in fields that are not usually affected. I have seen leafminer damage in Swiss chard, beets and even arugula, in addition to spinach this year.
From a distance, damaged leaves will appear to have blisters – white squiggles on the leaves. When you take a closer look, you may be able to see the legless, yellowish-white larva burrowing between the leaf layers. When the larva is mature, it will cut a hole in the leaf, drop to the ground and pupate. Two to four weeks later it will emerge as an adult fly. The flies are small – 1/4-inch long. Apparently, they are gray with black bristles, but without a hand lens they look like any other small fly to me – perhaps a little slimmer. The adult flies lay clusters of small, white eggs on the leaves.
Usually early spring plantings escape damage. This year the soil temperatures warmed up sooner in places – possibly contributing to earlier than normal problems.
What can you do? Start with cultural controls. Once the leafminer larvae are inside the leaf they are relatively protected from pesticide applications. Crop rotation is important for leafminers. Spinach, beets and Swiss chard (and apparently arugula) are hosts. Make sure you plant in an area that has not seen these crops for two to three years. The spinach leafminer flies overwinter in or near spinach fields and emerge in April and May to lay eggs. Planting early or overwintering spinach can help you escape significant damage, especially if you will be harvesting before mid-May. Deep spring plowing can also reduce the numbers of overwintering fly pupae.
In smaller plantings, they recommend using row cover. The row cover keeps out the egg-laying adults. Install the row cover immediately when you plant, and keep it in place until harvest. One note of caution: If you place row cover over beds that have overwintering leafminers or flies enter under the row cover, you are trapping them inside. The naturally-occurring predators and parasitoids would normally be helping you keep the populations down. Instead, you have created a haven for leafminers and they will multiply!
Unfortunately, if you have significant leafminer problems now, it is hard to go back and do cultural controls. If possible, it is a good idea to pick and destroy leaves with leafmining damage before the larvae emerge and lay eggs for the next generation. On a small scale it is possible to scout for and destroy eggs. For organic growers, Entrust is the only labeled product that has shown any efficacy in research trials. It will penetrate leaves and so it has more activity. Other products, including garlic, may be effective; unfortunately research trials are lacking to back them up. I have also heard of growers using beneficial nematodes. Non-organic growers can use abamectin, cyromazine, dinotefuran, permethrin and
spinosad products.
See the 2010 Production Guide for Organic Spinach at www.nyipm.cornell.edu/organic_guide and Commercial Vegetable Production Recommendations at http://horticulture.psu.edu/node/465 for details.
Tuesday, May 18, 2010
Insect Resistance to a GM Crop
Monsanto has revealed that a common insect pest has developed resistance to its flagship genetically modified (GM) product in India. The agricultural biotechnology leader says it "detected unusual survival" of pink bollworms that fed on cotton containing the Cry1Ac gene from the bacterium Bacillus thuringiensis, which codes for a protein that's toxic to many insect pests. In a statement to Science, Monsanto claims that the finding from western India "is the first case of field-relevant resistance to Cry1Ac products, anywhere in the world."
From: Science 19 March 2010:Vol. 327. no. 5972, p. 1439 "Hardy Cotton-Munching Pests Are Latest Blow to GM Crops Pallava Bagla"
DOI: 10.1126/science.327.5972.1439
From: Science 19 March 2010:Vol. 327. no. 5972, p. 1439 "Hardy Cotton-Munching Pests Are Latest Blow to GM Crops Pallava Bagla"
DOI: 10.1126/science.327.5972.1439
Sunday, November 22, 2009
Growers Visit Juniperdale Farm to View Cover Crops
Brian Fulmer of Juniper Dale Farm in Pen Argyl, PA told a group of local farmers his reasons for wanting to experiment with cover crops this year: To keep the soil in place, as well as to increase the nitrogen supply in his soil for sweet corn next year. “In other words,” he says, “the whole nine yards.”
Northampton County Cooperative Extension is taking part in an 11-county wide study of cover crops in Pennsylvania. They are using 15 different crops including: Aroostock Rye, Tillage Radish, Oats, Crimson Clover, Annual Ryegrass, Wheat, Triticale, Austrian Winter Pea, Hairy Vetch (Lancaster County), Hairy Vetch (Texas), Persian Clover, and Red Clover, as well as different combinations of the plants. The experiment looks at how well the different cover crops grow in local conditions and the most effective planting time.
Each plant has its own advantage. Winter pea is high in nitrogen. Rye has excellent nutrient uptake ability. Tillage radishes work as a “bio drill” (it breaks up the soil for your future crops). But they also have their disadvantages (some are very hard to control). After walking around the 15 different plots and discussing the soil and cost benefits of the different crops, the group of cover crop-curious farmers were left on their own to decide which cover would be the best for their own farms and soils.
Remember cover crops are an excellent way to stem soil erosion and depending on the crop you choose, can help enrich your soil with nutrients leading to healthier crops in the years to come.
Northampton County Cooperative Extension is taking part in an 11-county wide study of cover crops in Pennsylvania. They are using 15 different crops including: Aroostock Rye, Tillage Radish, Oats, Crimson Clover, Annual Ryegrass, Wheat, Triticale, Austrian Winter Pea, Hairy Vetch (Lancaster County), Hairy Vetch (Texas), Persian Clover, and Red Clover, as well as different combinations of the plants. The experiment looks at how well the different cover crops grow in local conditions and the most effective planting time.
Each plant has its own advantage. Winter pea is high in nitrogen. Rye has excellent nutrient uptake ability. Tillage radishes work as a “bio drill” (it breaks up the soil for your future crops). But they also have their disadvantages (some are very hard to control). After walking around the 15 different plots and discussing the soil and cost benefits of the different crops, the group of cover crop-curious farmers were left on their own to decide which cover would be the best for their own farms and soils.
Remember cover crops are an excellent way to stem soil erosion and depending on the crop you choose, can help enrich your soil with nutrients leading to healthier crops in the years to come.
Friday, November 20, 2009
Are you using more compost or manure than you should?
“Putting on too much compost is expensive and it pollutes.” - Klaas Martens. Organic Grain Farmer. Finger Lakes, New York.
We all know that using organic nutrients such as compost and manure have many benefits. They can increase organic matter, improve soil structure and build a reserve of nutrients in the soil. But the difficulty with using compost and manure is they release nutrients slowly at rates that we cannot always predict. Often the ratios of nitrogen to phosphorus and potassium don’t match what our plants need.
Recently I learned that there can be too much of a good thing. I spoke last week to Klaas Martens an organic grain farmer in the Finger Lakes region of New York. Working with Thomas Bjorkman, a researcher from Cornell, they applied a poultry based compost at different rates in order to determine if they could predict the best compost applications using traditional soil test recommendations. They found that compost applied at rates based on the soil test, did not increase yields or increase organic matter. But, weeds grew better! Where compost was applied at double the recommended rate, weeds were twice as tall (Bjorkman, 2008).
Over application severely impacts the environment. Agriculture account s for 73% of nitrogen and 64% of phosphorus in the Chesapeake Bay. Excess nitrogen easily leaches into ground water and into streams. Phosphorus binds tightly to soil particles that are washed into streams. These nutrients encourage growth of algae and aquatic weeds that use up the oxygen dissolved in the water, making it impossible for fish and other organisms that need this oxygen to survive.
Even the best organic farmers commonly over apply. Researchers surveying organic farms in the Northeast found that vegetable farms that relied on compost often had surplus nutrients, as much as 180-200 lb P and N/ acre – yr in excess (Drinkwater et. al. 2005).
It is easy to apply too much. We often apply at a rate of 1” or 2”s which is easier than calculating how many tons we are applying. Researchers at Penn State did just this, applying 1” or 2” of dairy based compost compared to inorganic fertilizer before peppers. They found that adding just 1” of compost released 441 lbs N/acre compared to the 100 lbs N/acre the peppers needed. This was considering that compost generally only releases 15% of its N per year. Another 2,450 lbs of N/ acre was still tied up in soil organic matter (Sanchez, 2008).
Don’t guess, soil test. Test your compost and soil. If your soil nutrients are too high (over 320 P2O5, 335 K2O, 2505 CaO, 490 MgO lbs/ acre), compost may not be the best choice this year. You will know your soil test is saying you are to high when the bars go into the “exceeds crop needs” section of the table.
Don’t guess, compost test. There is no such thing as the average compost. The average nitrogen content of 126 dairy manure based compost samples analyzed at Penn State was 1.45% nitrogen. But when we looked at three individual dairy manure compost samples from the same farm, the amount of nitrogen applied in 20 ton/ acre of compost ranged from 510, to 415 to 842 lb/ acre. Phosphorus ranged from 88, to 146 to 200.
If your soil test is okay calculate how much N,P,K is available based on your compost test. The compost you apply will be decomposed by bacteria and fungi that live in the soil which release the nutrients slowly over time. Use simple calculations available in Penn State publications “Managing Organic Nutrient Sources” to evaluate how much compost to apply to meet your crop needs. We have also put together a flow chart to help you decide which calculations to do for your farm. Ask for the “Organic Nutrient Sources Decision Making Tree.”
We all know that using organic nutrients such as compost and manure have many benefits. They can increase organic matter, improve soil structure and build a reserve of nutrients in the soil. But the difficulty with using compost and manure is they release nutrients slowly at rates that we cannot always predict. Often the ratios of nitrogen to phosphorus and potassium don’t match what our plants need.
Recently I learned that there can be too much of a good thing. I spoke last week to Klaas Martens an organic grain farmer in the Finger Lakes region of New York. Working with Thomas Bjorkman, a researcher from Cornell, they applied a poultry based compost at different rates in order to determine if they could predict the best compost applications using traditional soil test recommendations. They found that compost applied at rates based on the soil test, did not increase yields or increase organic matter. But, weeds grew better! Where compost was applied at double the recommended rate, weeds were twice as tall (Bjorkman, 2008).
Over application severely impacts the environment. Agriculture account s for 73% of nitrogen and 64% of phosphorus in the Chesapeake Bay. Excess nitrogen easily leaches into ground water and into streams. Phosphorus binds tightly to soil particles that are washed into streams. These nutrients encourage growth of algae and aquatic weeds that use up the oxygen dissolved in the water, making it impossible for fish and other organisms that need this oxygen to survive.
Even the best organic farmers commonly over apply. Researchers surveying organic farms in the Northeast found that vegetable farms that relied on compost often had surplus nutrients, as much as 180-200 lb P and N/ acre – yr in excess (Drinkwater et. al. 2005).
It is easy to apply too much. We often apply at a rate of 1” or 2”s which is easier than calculating how many tons we are applying. Researchers at Penn State did just this, applying 1” or 2” of dairy based compost compared to inorganic fertilizer before peppers. They found that adding just 1” of compost released 441 lbs N/acre compared to the 100 lbs N/acre the peppers needed. This was considering that compost generally only releases 15% of its N per year. Another 2,450 lbs of N/ acre was still tied up in soil organic matter (Sanchez, 2008).
Don’t guess, soil test. Test your compost and soil. If your soil nutrients are too high (over 320 P2O5, 335 K2O, 2505 CaO, 490 MgO lbs/ acre), compost may not be the best choice this year. You will know your soil test is saying you are to high when the bars go into the “exceeds crop needs” section of the table.
Don’t guess, compost test. There is no such thing as the average compost. The average nitrogen content of 126 dairy manure based compost samples analyzed at Penn State was 1.45% nitrogen. But when we looked at three individual dairy manure compost samples from the same farm, the amount of nitrogen applied in 20 ton/ acre of compost ranged from 510, to 415 to 842 lb/ acre. Phosphorus ranged from 88, to 146 to 200.
If your soil test is okay calculate how much N,P,K is available based on your compost test. The compost you apply will be decomposed by bacteria and fungi that live in the soil which release the nutrients slowly over time. Use simple calculations available in Penn State publications “Managing Organic Nutrient Sources” to evaluate how much compost to apply to meet your crop needs. We have also put together a flow chart to help you decide which calculations to do for your farm. Ask for the “Organic Nutrient Sources Decision Making Tree.”
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