See how soil fertility through long-term manure applications affects different crops.


This last year saw three interesting research studies on soil fertility, according to a Growing Produce article. The first looked at how long-term manure applications affect different crops. See a summary of the findings below.

Affecting Soil Fertility Through Long-Term Manure Applications


The study was conducted by the University of West Virginia over a span of 15 years. The team used 32 plots that were 400 sq.-ft each. Half of the plots were given high inputs of manure, and the other half were given low inputs. The locations of the different plots were randomized to minimize the impact of uncontrollable environmental factors.

The high-input plots received an annual application of 10 tons/acre of dairy manure. They were also planted with a rye-vetch cover crop in the winter. The low-input plots received no manure and the rye-vetch cover. Both plots also received a mixed-species hay mulch for two of every four years at a rate of 5 tons/acre.

The plots were planted with a variety of vegetable crops over the 15 years of the study.

Study Results


Researchers with the study maintained “Manure application in addition to green manures and hay mulch incorporation was found to result in significant economic returns,” in their report. The results of the study include:

1.      Soil organic matter for the high-test plot increased significantly, up to 8.7%, while the low-input plot only reached 5.4%.

2.      High-input plots had lower bulk density than low-input plots, and very high levels of phosphorus and potassium.

3.      Yields were much higher for high-input plots. Breakdowns of specific crops include:

·         Tomato: 9% higher

·         Pepper: 25% higher

·         Zucchini: 24% higher

·         Green bean: 24% higher

Read the complete report here: “Long-term Effect of Manure Application in a Certified Organic Production System on Soil Physical and Chemical Parameters and Vegetable Yields.”

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