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Nutrient Release from Living and Terminated Cover Crops Under Variable Freeze–Thaw Cycles
Author(s) -
Cober James R.,
Macrae Merrin L.,
Van Eerd Laura L.
Publication year - 2018
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2017.08.0449
Subject(s) - secale , frost (temperature) , agronomy , cover crop , phosphorus , vicia villosa , nutrient , biology , growing season , phosphorus deficiency , shoot , avena , chemistry , ecology , organic chemistry , geomorphology , geology
Core Ideas Light frosts did not increase phosphorus release from cover crops. Heavy frosts released more water‐extractable phosphorus than light frosts. Herbicide induced termination increased phosphorus and ammonium losses. Frost tolerant species released less phosphorus than frost‐intolerant species. Cover crops remain a suitable management practice in temperate regions.Cover crops (CC) are planted into fields during the non‐growing season as a best management practice (BMP) for agronomic and environmental benefits. However, freeze–thaw cycles (FTC) may increase the availability of water extractable P (WEP) from damaged plant tissues, leading some to question their efficacy as a nutrient BMP due to their potential to release P during snowmelt. The objectives of this study were to experimentally determine the influence of: (1) FTC magnitude (4°C, −4 to 4°C, –18 to 4°C, and –18 to 10°C), (2) CC species [cereal rye ( Secale cereale L.), oilseed radish ( Raphanus sativus L. var. oleoferus Metzg Stokes), red clover ( Trifolium pratense L.), oat ( Avena sativa L.), and hairy vetch ( Vicia villosa Roth)], and (3) termination using herbicide on the magnitude of WEP, NH 4 + , and NO 3 − release. Shoot tissue clippings underwent five FTC followed by extraction. Large magnitude FTC from –18 to 4 and –18 to 10°C (heavy frost) elevated WEP release, whereas the −4 to 4°C (light frost) treatment did not. Responses varied with plant type, where frost‐intolerant species released more WEP than frost‐tolerant species. In contrast, NH 4 + , and NO 3 − release did not increase following FTC. Termination elevated WEP and NH 4 + release across all temperature treatments. The use of CC as a nutrient BMP should be used with caution in some regions, but in areas with mild winter climates, growing frost tolerant species without termination may reduce the risk of P leaching from vegetation in winter and early spring.