No-till is challenged:Complementary management is crucial to improve its environmental benefits under a changing climate

Tillage is the most common agricultural practice dating back to the origin of agriculture.In recent decades,no-tillage(NT)has been introduced to improve soil and water quality.However,changes in soil properties resulting from long-term NT can increase losses of dissolved phosphorus,nitrate and some classes of pesticides,and NT effect on nitrous oxide(N_(2)O)emission remains controversial.Complementary management that enhances the overall environmental benefits of NT is therefore crucial.By incorporating cover crops,nutrient cycling and nutrient use efficiency in NT fields could be improved given the nutrient supplying capacity of some cover crops.Cover crops could also offset the need for occasional tillage of NT cropland,an operation whose effect is only temporary in reducing,for example,soil compaction associated with NT management.When used in combination with NT,cover crop termination methods,using agrochemicals,should be carefully considered to prevent further jeopardy to water quality.Compared to herbicides,the use of roller crimping could potentially result in production cost saving while minimizing soil disturbance and export of agrochemicals.Future research should focus on various combinations of cover crop traits(e.g.,decomposition rate)and management(e.g.,timing of cover crop termination)that account for site-and cash crop-specific requirements.

Nitrogen preference across generations under changing ammonium nitrate ratios

Aims Nitrogen(N)in natural environments is typically supplied by a mix-ture of ammonia(NH_(4)^(+))and nitrate(NO_(3)^(-)).However,factors that underlie either NH_(4)^(+)or NO_(3)^(-)preference,and how such preference will change across generations remain unclear.We conducted a series of experiments to answer whether:(i)NH_(4)^(+):NO_(3)^(-)ratio is the driving factor for plant N preference,and(ii)this preference is con-sistent across generations.Methods We conducted both:(i)field observations(as a proxy for parent or P generation)and(ii)greenhouse experiments(the first generation or F1 and the second generation or F2)using corn and soybean grown under different NH_(4)^(+):NO_(3)^(-)ratios.Important Findings Both corn and soybean had the physiological plasticity to pre-fer either NH_(4)^(+)or NO_(3)^(-)depending on NH_(4)^(+):NO_(3)^(-)ratios,and this plasticity was consistent across generations.Corn,however,showed a stronger preference towards NO_(3)^(-)while soybean showed a stronger preference towards NH_(4)^(+).While both plants would try to make use of the most available form of N in their growing medium,plant species,physiological characteristics(e.g.maturity)and plant nutrient status also determined the extent of N uptake.From the evolutionary and productivity perspective,this plasticity is benefi-cial,allowing plants to effectively acquire available N particularly in a changing climate.