alkaline in soil too high

Asked June 22, 2015, 8:16 PM EDT

The peas are up and the leaves are green but curling, the potatoes are up but like a stick and the leaves are curled, they staighten as they grow.What ever I plant such as flowers, zuchinni (spelling) all turn yellow and die.I did a ph test and it showed high in alkaline.A plant expert said to put lime in the soil.What is the cause of the dieing plants and how do I correct it.I've read to use peat, and manure, also surfur. Is lime alright?

Plymouth County Iowa

1 Response

Garden soils are often described as acidic or alkaline. The relative acidity or alkalinity of soil is indicated by its pH. The pH scale runs from 0 to 14. Any pH reading below 7 is acidic and any pH above 7 is alkaline. A pH of 7 indicates a neutral soil. The pH is important because it influences the availability of essential nutrients. Most horticultural crops will grow satisfactorily in soils having a pH between 6 (slightly acid) and 7.5 (slightly alkaline). Since most garden soils in Iowa are in this range, most gardeners experience few problems with soil pH.

There are a few plants that require a soil pH of 4.5 to 5.5. These "acid-loving" plants include azaleas, rhododendrons, and blueberries. The soil pH for these plants can be lowered by incorporating elemental sulfur (S) into the soil. Since the soil acidifying response to elemental sulfur is slow, it should be applied and incorporated a year before planting. Working sphagnum peat moss into the soil is another method to lower pH.

For most plants, however, a soil pH below 6.0 is undesirable. Strongly acid soils need to be limed to raise the pH to near neutral levels. Liming materials include ground limestone which is mainly calcium carbonate (CaCO3) and dolomitic limestone which contains CaCO3 and some magnesium carbonate (MgCO3). Since most Iowa soils do not need to be limed, apply liming materials only when recommended by a soil test.