An Interesting Green Manure Study         

A fourth-year project at the Agricultural Campus, Dalhousie University has studied the impacts of leguminous and non-leguminous green manure cropping systems on soil nitrogen mineralization. The purpose of this study was to find the most suitable strategy of applying legume and non-legume green manure crops for organic farming management in Truro, Nova Scotia.

For a comprehensive understanding about agriculture, the Agriculture Faculty of Dalhousie University gives students many opportunities to research what they are interested in during the undergraduate stage. Yanxiong Cheng, as the student in environmental science major, spent the time of 2016 and 2017 fall and winter terms on researching the soil impacts of leguminous and non-leguminous green manure cropping systems in Truro, Nova Scotia. Dr. David Burton, as the supervised professor who specializes in soil and climate change areas, provided incredible academic and technique supports during the whole study.


Figure 1. Brookside Experimental Site in Truro, Nova Scotia.

Chemical fertilizer pollution seriously influences food safety. Due to the increasing concern about the food security, organic products have become popular in the global market. Meanwhile, organic farming has increased with the improvement of agricultural technology. Further study is important for a better management of the organic farming.

Yanxiong found that the legume and non-legume crops played an important role in green manure management for organic farming. Legume green manure crop has a strong capacity to fix the soil nitrogen, meanwhile, non-legume green manure crop is able to remove some harmful weeds that occupy the major crop’s demands for nitrogen and soil fertility. This study, conducted in Truro, Nova Scotia, was designed to evaluate most suitable strategies that maximized the positive impacts of the application of leguminous, non-leguminous green manure cropping and their intercropping systems.

Interesting Field Soil Sampling

The field soil sampling was an interesting activity in the whole study. To meet the requirements of crop treatments, an integrated organic farming field was selected at Brookside Experimental Site in Truro, NS. The field provided not only legume and non-legume crops but also the inter-seeded legume and non-legume crops. “Although the weather was extremely cold in December, it was interesting and meaningful for the students to use the sampling tool, learn the practical sampling experience and feel the happiness when touching the soil and nature”, says Yanxiong.


Figure 2. Field soil sampling activity by Yanxiong at Brookside experimental site on December 2016.

Interesting Laboratory Soil Test

Laboratory soil test was another interesting activity. Supported by Dr. Burton, each soil sample was conducted through the Standard Operation Procedures of Soil Nitrogen Supply. To imitate and measure the nitrogen mineralization during the cropping season, these soil samples experienced a 14-day incubation at 25 °C (the optimal temperature of nitrogen mineralization). When the soil test completed, the data of soil mineral nitrogen and N flush were obtained for the statistical analysis and further discussion. To make sure the accuracy of results, each laboratory step was needed for the operator to be serious and rigorous.


 Figure 3. Soil Nitrogen Supply (SNS) analysis at the Soil Test Lab in the Agricultural Campus, Dalhousie University.

The results showed the leguminous and non-leguminous intercropping system preserved the highest soil mineral nitrogen content and promoted the highest soil nitrogen mineralization. The leguminous cropping system also performed high soil nitrogen mineralization during the cropping season. The intercropping application of the legume and non-legume crops maximized the positive impacts on soil nitrogen mineralization. This application could be the most suitable strategy for the management of green manure cover crops in Truro, NS.

This study was filled with interesting knowledge and practice, however, many unknown difficulties had occurred. Dr. Burton and other professional staff provided assistance and suggestions to help the student to handle relevant problems. “It is undeniable that this interesting green manure study has become an unforgettable experience in my life”, says Yanxiong.

There are many interesting opportunities about the agricultural research. These opportunities allow students to understand agriculture further in Faculty of Agriculture, Dalhousie University. Participating in agricultural studies and becoming an agriculture student is an incredible choice for discovering interesting things in plants, foods, environment sciences and more. You must have fun and enjoy the agriculture with your own achievement and value.

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