Organic grain producers are interested in reducing tillage to conserve soil and decrease labor and fuel costs. We examined agronomic and economic tradeoffs associated with alternative strategies for reducing tillage frequency and intensity in a cover crop–soybean (Glycine max L. Merr.) sequence within a corn (Zea mays L.)–soybean–spelt (Triticum spelta L.) organic cropping system experiment in Pennsylvania. Tillage-based soybean production preceded by a cover crop mixture of annual ryegrass (Lolium perenne L. ssp. multiflorum), orchardgrass (Dactylis glomerata L.) and forage radish (Raphanus sativus L.) interseeded into corn grain (Z. mays L.) was compared with reduced-tillage soybean production preceded by roller-crimped cereal rye (Secale cereale L.) that was sown after corn silage. Total aboveground weed biomass did not differ between soybean production strategies. Each strategy, however, was characterized by high inter-annual variability in weed abundance. Tillage-based soybean production marginally increased grain yield by 0.28 Mg ha−1 compared with reduced-tillage soybean. A path model of soybean yield indicated that soybean stand establishment and weed biomass were primary drivers of yield, but soybean production strategy had a measurable effect on yields due to factors other than within-season weed–crop competition. Cumulative tillage frequency and intensity were quantified for each cover crop—sequence using the Soil Tillage Intensity Rating (STIR) index. The reduced-tillage soybean sequence resulted in 50% less soil disturbance compared to tillage-based soybean sequence across study years. Finally, enterprise budget comparisons showed that the reduced-tillage soybean sequence resulted in lower input costs than the tillage-based soybean sequence but was approximately $114 ha−1 less profitable because of lower average yields.
Reducing the intensity and frequency of tillage in organic grain production systems is likely to produce several agronomic, economic, and environmental tradeoffs. We evaluated four organic corn (Zea mays L.) sequences in a 3‐yr, full‐entry organic cropping systems experiment. Two sequences included a hairy vetch (Vicia villosa Roth)/triticale (Triticale hexaploide Lart.) mixture sown after spelt harvest that differed in tillage practices (no‐till [NT], conventional) before corn and corn harvest management (silage, grain). Two sequences included a red clover (Trifolium pretense L.)/timothy (Phleum pretense L.) mixture frost‐seeded into spelt in late winter followed by conventional tillage preceding corn and either silage or grain harvest. Our results showed that late‐season weed biomass did not differ across alternative sequences, although both tillage and NT corn production resulted in high in‐row weed pressure in different years. Cover crop management prior to tillage‐based corn production did not affect grain yields, but NT silage production resulted in lower yields compared with the tilled sequence. Corn silage yields were positively correlated with corn populations in both tilled and NT systems. The NT sequence lowered tillage frequency and intensity by 39 and 52%, respectively, compared with tillage‐based corn production as measured using established metrics, including the soil disturbance rating, but did not significantly influence labile carbon pools. Sequences using underseeded red clover resulted in higher net returns compared with hairy vetch sequences due to additional income from fall forage harvests.
If you are pursuing your doctoral degree, chances are you will have to take comprehensive exams (also referred to as "comps," preliminary exams, or "prelims") in the near future. These exams test the breadth and depth of what you know, and also what you don't know, to determine if you are ready to be considered a candidate for your doctoral degree and make the transition from coursework into the dissertation process. While every school or department may have a different exam format, planning ahead, developing good study habits, and managing stress are key for exam preparation. Comprehensive exams can be extremely stressful and difficult but also very rewarding. The preparation tips below are a good starting point for initiating the studying process and conquering your exams.
Graduate school can take a lot out of you. Between research, classes, and your personal life, it can be difficult to balance everything. Many students must also take on a job outside of academia, or they may have children to raise. The demands of graduate school can affect your mental health in a number of ways. Graduate students report struggling with mental health at a rate six times higher than the general public. If you are struggling with mental health in graduate school, you are not alone. Below you will find some mental wellness tips as well as a number of resources available for graduate students to utilize. Facts about Mental Health in Grad StudentsMany factors contribute to a student's mental health, including work-life balance, supervisor relationships and leadership style, and academic commitments. Survey studies have found that more than 40% of graduate students deal with mental health issues. These can be things such as anxiety, depression, sleep disorders, eating disorders, and substance abuse. More than 50% of graduate students feel that their work-life balance is unhealthy and contributing to mental health struggles, and the same percentage feel as though their adviser/PI does not provide them with enough support or mentorship. Additionally, many students struggle to reach out for help due to the continued stigma around mental health, especially in academia. Mental Wellness Strategies Setting BoundariesBoundaries are a tool that can be helpful in any relationship, but you may receive pushback depending on how the other parties involved
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