Agriculture Reference
In-Depth Information
marks or ranges in pH, soil nutrient concentrations, and organic matter. We
have similar standards for foliar nutrient concentrations, as we will discuss
ply and help you monitor changes in your orchard over time. The goal is to
create and maintain a stable, pH-appropriate, nutrient-rich, biologically act-
ive soil.
Soil pH
A soil's pH affects the availability of mineral nutrients to plants, so it's im-
portant to get it right. Remember that a pH of 7.0 is neutral. Values above
that are alkaline (basic) and those below 7.0 are acidic. A laboratory will
provide the most accurate analysis, although there are several types of kits
you can purchase to measure pH yourself. A handheld pH meter purchased
from an agricultural or laboratory supply company will provide accurate res-
ults when used properly and can be a good investment for growers who wish
to test soil pH frequently. You can also purchase one of several “color kits”
for measuring soil pH and nutrient concentrations. Some are extremely ac-
curate (and expensive!) while others provide poor accuracy. For serious fruit
growers, it is best to send a sample to the laboratory or purchase a good-
quality pH meter. Simple pH “meters” with metal probes are readily available
in garden centers, but these often provide very poor accuracy and should be
avoided.
acid-loving crops, temperate zone fruit crops grow and produce best on soils
that are slightly to moderately acidic. As the soil becomes more strongly
acidic (lower pH), the macronutrients nitrogen, phosphorus, potassium, mag-
nesium, calcium, and sulfur become less available to plants, as does the mi-
cronutrient molybdenum.
As soils become alkaline, the micronutrients boron, cobalt, copper, iron,
manganese, and zinc become less available. At pH values above roughly 7.5,
iron chlorosis often develops in apples, peaches, cherries, and other fruit tree
crops. This disorder is characterized by yellow to white leaf blades with dark
