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On August 03, 2019

To Manage Soil Fertility To Establish Or Renovate Hay Or Pasture 

Late summer is a time when many farmers may be thinking about renovating or establishing a hay or pasture field.  This is a good spot in the lifecycle of a hay or pasture field to assess soil fertility and make corrections as needed so that the time and expense put into a seeding will yield healthy crops for the years to come.  Extension Soil Fertility Specialist Charlie White explains the key soil fertility parameters to assess are pH, phosphorus (P) and potassium (K).  It is also important to consider whether soil preparation for the seeding will be no-till or tillage based, as this can affect the soil sampling depth and the behavior and efficacy of fertilizer and lime applications.

Making soil fertility adjustments should be based on a soil test report, otherwise you are shooting in the dark to determine rates of lime and fertilizer applications.  Regular soil fertility samples are usually taken from the surface to a depth of 6 or 8 inches.  However, in permanent pastures or hay fields that have been in long-term no-till, sampling to a depth of only 3 to 4 inches is recommended.  On the soil sample submission form, enter the crop type that will be grown in the field and the estimated yields for the establishment/renovation year as well as subsequent years.  Often the yield is lower in the establishment/renovation year, and the fertilizer recommendation will be adjusted for this.  Recommendations from the Penn State Agricultural Analytical Services lab use a “build and maintain” philosophy, so the recommendation will have a component designed to build fertility levels into the optimal range, and then a component to maintain levels in the optimum range using estimated crop removal levels based on yields.  If soil test levels of P or K are above optimum already, the soil test recommendation will be to not add any additional fertilizer so that soil test levels can draw down into the optimum range.

Maintaining soil pH levels in the optimum range is important for legume crops as well as for maintaining the efficacy of some herbicides.  Alfalfa and other forage legumes require a pH closer to neutral, with an optimum range between 6.5 and 7.0, for the rhizobial bacteria to effectively fix nitrogen (N).  Grass forages have an optimal pH range of 6.0 to 6.5.  If the pH is below optimum through the whole “plow layer,” it is best to incorporate the recommended amount of limestone with tillage.  Otherwise the limestone’s neutralizing ability may not penetrate much below the soil surface for many years.  

In long-term no-till systems, including permanent pastures, liming management requires additional monitoring.  If the soil has not been limed recently, a layer of acidity can develop at the soil surface due to surface applications of nitrogen fertilizer.  A soil test pulled to 4 inches or more may not detect this “acid roof,” however.  Correcting this surface acidity is important to prevent acidity from reaching deeper into the soil, where it is difficult to manage in no-till systems.  It is also important to maintain the efficacy of some herbicides.  In these no-till scenarios, if your regular soil fertility sample indicates a need for lime, follow that lime recommendation and apply it to the soil surface without incorporation.  If your regular soil fertility sample does not indicate a need for lime, you should go back and take a sample to 1 or 2 inch depth to check for an acid roof.  If the pH of this sample is less than 6.0, then apply 1 ton/ac of limestone to the soil surface to neutralize the acidity.

Phosphorus behavior in the soil warrants special attention relative to no-till scenarios as well.  Phosphorus is an immobile nutrient, so P applied to the soil surface will not penetrate deeply into the rooting zone.  Phosphorus broadcast onto the soil surface also has a higher risk of running off into nearby surface waters, where it becomes a pollutant.  If the soil test calls for a P recommendation, consider using an application method that incorporates the fertilizer into the soil with low disturbance.

Manure can be a good source of nutrients to meet the soil fertility needs of pastures and hay fields, with some important considerations.  In addition to P and K, manure is a source of N.  In establishing or renovating hay fields and pastures, excess N can be detrimental.  In mixed grass and legume plantings, N can stimulate the growth of the grasses, suppressing the legume component.  It can also stimulate weed growth.  For plantings or renovations of pure grass stands, only 20-40 lbs. N/ac is necessary at establishment.  In no-till settings, if the manure is not incorporated, much of the ammonium fraction will volatize in the warm summer months, reducing the overall N availability.  Therefore, if using manure as a fertility source, consider how the manure type and the application method will affect the N availability and use a low enough rate so as to minimize adverse effects from the N addition.

Paying attention to soil fertility details at this stage in the lifecycle of a pasture or hay field will help to maintain productivity over the long-term.  

To Take Your Family To Ag Progress Days

Ag Progress Days (APD), Pennsylvania’s largest outdoor agricultural exposition will be held August 13-15, 2019. The show is held annually, for three days in August, at The Pennsylvania State University’s Research Farms. Ag Progress Days features the latest technology and research exhibits, educational programs, and guided tours. Sponsored by Penn State’s College of Agricultural Sciences, the event celebrates the forty-fourth year to be held at the Russell E. Larson Agricultural Research Center at Rock Springs, nine miles southwest of State College, PA. It is one of only three agricultural exhibitions in the country sponsored by a major University. Our exhibits showcase the latest in Penn State research, as well as information on best management practices and changing regulations in the agricultural industry. There are activities for family members of all ages. For more information see the website: https://agsci.psu.edu/apd/about 

Quote Of The Week: “If you can’t see the bright side, polish the dull.” Amish Proverb by Suzanne Woods Fisher