Impacts of very tall stubble on pulse crop morphology and productivity in the nothern Great Plains

Abstract

Soil water conservation is crucial for productivity of dryland agricultural systems in the semiarid Northern Great Plains (NGP). Erosion concerns are prevalent among pulse crop producers across this region due to lack of post-harvest crop residues. Field-scale trials examined very tall (>60 cm) versus short (<20 cm) cereal stubble at Geraldine and Moccasin, MT, 2024. A plot-scale study in Bozeman and Moccasin, MT, in 2024, assessed pulse crop morphology and productivity in tall (>45 cm) versus short (<10 cm) stubble under rolled and unrolled treatments. Field-scale results showed increased overwinter soil water storage in tall stubble at Geraldine, with observed increases in chickpea (Cicer arietinum L.) biomass, seed yield, plant height, and basal pod height in tall stubble. However, a higher clay content within the tall stubble boundary likely contributed to these observed increases. For field pea (Pisum sativum L.) at Moccasin, only basal pod height increased in tall stubble. Tall stubble provided greater soil coverage pre-seeding and post-harvest, likely mitigating wind erosion risks. At the plot scale, basal pod height increased in tall stubble for chickpea (9.2%), lentil (Lens culinaris Medik.) (14%), and pea (7.2%) at Bozeman, improving harvestability. Chickpea plant height increased by 10%. At Moccasin, lentil basal pod height increased by 19%. Chickpea biomass increased by 17% in tall stubble at Bozeman only, with no biomass differences observed for lentil or pea at either site. Lentil yield at Bozeman increased by 10% in tall stubble, with no other yield differences observed. A rolling treatment effect was observed for chickpea biomass at both locations, increasing by 47% and 18% in the tall*rolled treatment compared with the short*rolled treatment at Geraldine and Moccasin, respectively. Notably, lentil plant density decreased in tall stubble by 12% at Bozeman. Importantly, it was observed that tall stubble integrity was greater at field- than plot-scale, where various plot-scale activities knocked down a much greater proportion of tall stubble. These results highlight the variable effects of tall cereal stubble on pulse crops, where tall stubble management generally offers agronomic and conservation benefits for dryland cropping systems in the NGP.