{"id":167,"date":"2017-01-11T08:00:20","date_gmt":"2017-01-11T16:00:20","guid":{"rendered":"http:\/\/blogs.cdfa.ca.gov\/FREP\/?p=167"},"modified":"2026-04-02T13:09:26","modified_gmt":"2026-04-02T20:09:26","slug":"research-update-n-fertilizer-requirements-of-crops-following-alfalfa","status":"publish","type":"post","link":"https:\/\/blogs.cdfa.ca.gov\/FREP\/index.php\/research-update-n-fertilizer-requirements-of-crops-following-alfalfa\/","title":{"rendered":"Research Update: N Fertilizer Requirements of Crops Following Alfalfa"},"content":{"rendered":"

Research Project:<\/strong> Characterizing N Fertilizer Requirements of Crops Following Alfalfa – Putnam, D. et al.<\/i><\/p>\n

\"In<\/a>

In Davis, strips of alfalfa and wheat-sudangrass rotations were established to compare the effects on a wheat crop planted after both systems. Yields of wheat at different N rates were then compared.<\/em><\/p><\/div>\n

Issue:<\/strong> Alfalfa is a leguminous crop that converts atmospheric nitrogen (N) into organic compounds. While it is well-known that crops following alfalfa benefit from the residual N produced by alfalfa, the amount of residual N has rarely been measured. Previous estimates of N carryover from alfalfa range from 40 to 80 lb. of N per acre. This project is aimed at characterizing the residual N available for crops rotated after alfalfa.<\/p>\n

Methods\/Locations:<\/strong> Field-scale experiments were established at Davis, Tulelake, and Kearney, CA, and the effects of various rotations on N accumulation in wheat were examined.<\/p>\n

Main findings:<\/strong> The investigators found that wheat following alfalfa realized N credits of 70 to 130 lb. of N per acre, depending on location, soil type and other factors. This is a significantly larger credit than has been previously estimated.<\/p>\n

The researchers suggest that these amounts should be adjusted based upon other parameters that may influence N availability. These may include: whether the stand was adequate, whether foliage was vigorously growing when plowed down, plants per square foot, the degree of weed intrusion, soil-type, etc. Additionally, the time elapsing between plow-down and wheat planting must also be considered, since some of this N may be lost during crop rotation.<\/p>\n

Crop rotation with alfalfa caused improvements in wheat protein at virtually all N rates applied to the subsequent wheat. This is important since much of the N applied to wheat has the objective to improve wheat protein, which brings a premium to the grower.<\/p>\n

Potential Impact:<\/strong> Typically a minimum of 150,000 acres of alfalfa are rotated to other crops each year in California. If a conservative estimate of 80 lb. of N per acre credit is accounted for in the crops following alfalfa across the state, 2 million pounds of N fertilizer could be conserved each year. This would reduce production and labor costs incurred by growers and benefit the environment.<\/p>\n

Full Project Report:<\/strong> https:\/\/www.cdfa.ca.gov\/is\/docs\/12-0385-SAPutnam.pdf<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Research Project: Characterizing N Fertilizer Requirements of Crops Following Alfalfa – Putnam, D. et al. Issue: Alfalfa is a leguminous crop that converts atmospheric nitrogen (N) into organic compounds. While it is well-known that crops following alfalfa benefit from the residual N produced by alfalfa, the amount of residual N has rarely been measured. Previous estimates of N carryover from …<\/p>\n

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