Richard Taylor, Extension Agronomist; email@example.com and Phillip Sylvester, Kent Co., Ag Agent; firstname.lastname@example.org
Another field of barley with severe deficiency symptoms showed up in Kent County this past week. Although the field had received ammonium sulfate this spring, the rate used provided only about 10 to 15 lbs of S per acre, which is less than the crop requirement. If the low S fertilization rate is coupled with the heavy rainfall many areas have experienced over the past several weeks, it would not be surprising that a significant amount of the sulfate-S has leached below the rooting zone of barley. In this case, although the visual symptoms (Photo 1 and 2) suggested sulfur (S) deficiency with general chlorosis of the leaves, especially the newest leaves, and shortened plants, the soil test suggested that S was not the only deficiency likely to impact barley yield even if sulfur were added (Table 1). On the bad sample note the low soil organic matter (SOM) level (0.9%) and the impact on the cation exchange capacity (CEC) of the soil (2.1 meq/100 grams of soil in the bad area versus 3.6 meq/100 grams of soil in the good area). The CEC impact was also evident in the amount of potassium (K) and magnesium (Mg) that the soil could hold.
Photo 1. Close-up of deficient barley plants showing general chlorosis, especially in newest leaves, and stunting.
Photo 2. Field view of deficient barley plants showing general chlorosis and stunting compared with less affected plants in the background.
The short term solution to the problem is the addition of K-Mag (0-0-22-11Mg-22S) fertilizer to the field. However, the soil test results suggest that on a longer-term horizon, the critical need of the field is the addition of organic matter, either as green manure crops, compost additions, or manure additions. Trying to maximize the amount of crop residue and minimize the amount of SOM mineralization due to tillage operations is also recommended. The use of winter cover crops and green manure crops whenever the field is not being cropped will gradually raise the SOM levels, as will any additions of manures or composts. Not only with organic will additions help raise the CEC and soil nutrient holding capacity but will also help increase water holding capacity and improve yields in the long run.
Table 1. Soil test report on barley field comparing good and bad areas.
|Good Barley||Bad Barley|
|Soil pH 1:1||6||6.3|
|Organic Matter %||2.4||0.9|
|U of D P Sat Ratio||39||59|
|Mehlich3 Phosphorus ppmP/FIV||193||144|
*Indicated Base Saturation