Blog 6 - Soils

What are the most common soil types the region in the USA where pecans are cultivated?

We will discuss the soils of the states Georgia and Texas. 

Georgia

Figure 1 the soils in Georgia. (University of Georgia: College of Agriculture & Environmental Sciences, 2017).

-          Limestone valley

The area in the Limestone valley alternates between hard and soft rock. The ridges are formed out of hard rock, but the valleys consist of softer limestone, shale and other material. (Coleman, n.d.)

-          Blue Ridge

There is a rich ecosystem with a diversity of plants and animals. The soil is loamy. It consists of clay, silt and sand. It looks brown and it is acidic. (Coleman, n.d.).

-          Southern Piedmont

The soil in Piedmont consists mostly out of granite and clays. It is famous for its red clay, which consists of silicon, aluminum, iron oxide and other elements. (Coleman, n.d.).

-          Sand Hills

The sand hills are found between the Southern Coastal Plain and Southern Piedmont soils. (See Figure 1). On this soil type it is very hard to use for agricultural purposes.

-          Atlantic Coast Flatwoods

       In the Coastal area one can find a variation of soils, such as: red clay, sands and gravels. In the Atlantic Coast Flatwoods most of the agricultural soil can be found. (Coleman, n.d.).

-          Southern Coastal Plain

In the Southern Coastal Plain more sandy and nutrient-poor soils are found. (Coleman, n.d.).

Texas

-          Backland soil

Backland soil is thick black clay and alkaline. It is considered very fertile because it has a high calcium content. It is found in East-Central Texas. (Golberg, 2017).

-          Sandy loam

It is a mixture of sand and red clay and is very acidic. The red clay is rather difficult to manage. This type of soil is found in the East. (Golberg, 2017).

-          Sand

In the area between backland soil and the sandy loam there is an area with sand as soil type. Needless to say, cultivation of crops on this soil type is very difficult. (Golberg, 2017).

-         Yellow clay

In the west of San Angelo yellow clay can be found. The soil is limestone with thin layer of yellow clay on top. The soil is very alkaline and it is very hard to manage agriculture in this area. (Golberg, 2017).

-          - Alluvial soil

This soil type is mostly found in the Western Gulf Coastal region. It is also referred to black as gumbo clay and is very heavy and acidic. The clay holds water easily and due to the frequent rainfall it is likely to remain damp. In some locations the high salt content of the clay can provide problems. (Golberg, 2017).

What are the nutritional requirements for pecans?

Nitrogen and zinc are the two nutrients often most required by pecan trees. By this is meant that these minerals are most prone to have to be added for they are sometimes not available in the required quantities in nature. Phosphorus and potassium, however, are rarely needed in pecans. (Chapman & Garcia, n.d.).

Table 1. The Nutrient suffiency rates of the pecan tree.

Macronutrients	Sufficiency rates
Nitrogen	2.5 – 3.3 %
Phosphorus	0.12 – 0.3 %
Potassium	1.25 – 2.5 %
Magnesium	0.35 to 0.6 %
Micronutrients
Zinc	50 to 100 ppm
Iron	50 to 300 ppm
Boron	50 to 100 ppm
Nickel	>3 ppm
Copper	6 to 30 ppm

(Logan, 2017).

In the desert Southwest often nitrogen and zinc are the main ingredients that are supplied to commercially grown pecan trees. (Walworth , 2013).

Annually, an average of 100 to 500 lbs/a of Nitrogen is applied to the orchards. The Nitrogen fertilization is considered essential for impacting pecan yield and nut quality. (Walworth , 2013). Animal manure is high in nitrogen, especially poultry manure does well. (Chapman & Garcia, n.d.).

Pecans growing in chalky, alkaline soils are especially susceptible to Zinc deficiency because soluble zinc reacts with carbonates and hydroxides reducing its availability to plants. And average of 12 to 40 lbs Zn/a is added in a commercial orchard in Arizona. (Walworth , 2013). Zinc is naturally found in rocks, but poultry manure can add considerable amounts of zinc to the soil. Broiler littler contains 0.01-0.5 lb zinc/ton and laying hen litter has approximately 0.15 lb/zinc/ton. (Sutradhar, Kaiser, Rosen, & Lamb, 2016).

References

Chapman, D., & Garcia, M. (n.d.). Fertilizer and Cultural Recommendations for Pecan Trees. Retrieved from University of Arkansas: https://www.uaex.edu/publications/PDF/FSA-6131.pdf

Coleman, D. C. (n.d.). Soils. Retrieved from Georgia Encyclopedia: http://www.georgiaencyclopedia.org/articles/geography-environment/soils

Golberg, J. (2017, September). The Types of Soil in Texas. Retrieved from Garden Guides: http://www.gardenguides.com/108484-types-soil-texas.html

Logan, D. (2017, September 21). What Nutrients Do Pecan Trees Need? Retrieved from Garden Guides: http://www.gardenguides.com/106127-nutrients-pecan-trees-need.html

Sutradhar, A., Kaiser, D., Rosen, C., & Lamb, J. (2016). Zinc for crop production. Retrieved from University of Minnesota Extension: http://www.extension.umn.edu/agriculture/nutrient-management/micronutrients/zinc-for-crop-production/

University of Georgia: College of Agriculture & Environmental Sciences. (2017). Soil Fertility in Pastures and Hayfields in Georgia. Retrieved from University of Georgia: College of Agriculture & Environmental Sciences: http://georgiaforages.caes.uga.edu/SoilProv.html

Walworth , D. (2013). NUTRIENT MANAGEMENT IN PECANS. Retrieved from University of Arizona, Tucson: http://www.ipni.net/ipniweb/conference/wnmc.nsf/e0f085ed5f091b1b852579000057902e/211da715452ce0aa85257bf8004df04d/$FILE/WNMC2013%20Walworth%20pg121.pdf