Studying Stover Harvest Effects on Yield, Soil, Climate

Corn stover has been used for many years as bedding and food for livestock, as well as to nourish and protect soils. In recent years, the ubiquitous stalk, leaf and cob residue of corn plants left in fields after harvest has found a new market: as a potential source for cellulosic ethanol production

Flooded Soil Syndrome

Fallow Syndrome is a condition where crops planted the year after an extended period with no plant growth exhibit reduced early growth and yield. On corn plants the syndrome exhibits classic phosphorus (P) deficiency symptoms, including slow-stunted early growth, purple coloration, and poorly developed roots. This effect is called Fallow Syndrome because it is observed in soils where, for moisture conservation, the land has been idled for a year and kept fallow with no crop or weed growth. This allows accumulation of moisture in the soil for the next cycle of crop production.https://lib.dr.iastate.edu/extension_pubs/1118/thumbnail.jp

Iowa Experience with the Illinois N Test

An important aspect for estimating optimal N applications is to predict the soil N supply capacity (ability to supply plant-available N) each year. Since fertilizer applications supplement crop N requirements that the soil system cannot meet, understanding potential plant-available N originating from the soil can aid in setting N fertilization rates. General differences in plant-available N and fertilization need between fields are commonly accounted for through effects of crop rotation. An example of further refinement is the grouping of similar N responsive soils by yield potential (Vanotti and Bundy, 1994), as is done in Wisconsin for corn N fertilization. Determining soil N supply (N responsiveness) through soil testing has received considerable attention over the years. Most commonly used tests measure soil nitrate, either nitrate already present in the soil (post-harvest profile nitrate or preplant profile nitrate - PPNT) or a combination of nitrate present in the soil and that mineralized in the early spring (presidedress soil nitrate – PSNT or late spring soil nitrate – LSNT). For various reasons (time of sampling, sample depth, sampling difficulties, reliability) these tests have not been widely used in the north-central USA (Fox et al., 1999). Many other soil tests, based on various chemical extraction or biological incubation methods, have been studied over the years as potential indicators of mineralizable-N (examples in Bundy and Meisinger, 1994). However they have either not been successful in quantifying potential plant-available N or are not suitable for routine analysis

Corn Residue Harvesting Effects on Yield Response to N Fertilization

Producers have many choices of diverse tillage practices for their corn (Zea mays L.) production systems. However, no-till has become an important soil management practice to help reduce water and wind erosion, as well as nutrient runoff, while conserving soil moisture for crop use. No-till systems also help farmers by saving labor and time, as well as reducing farm costs due to less equipment and fuel consumption. Nevertheless, no-till production is typically more successful and has higher crop yield on moderately to well drained medium-textured soils (Bitzer, 1998), compared to soils with poor internal drainage and high clay

Corn Following Corn in 2008

Corn following corn is in rough shape in areas across Iowa. Many wonder what is happening. The crop’s condition in general is not normal for this time of year. For example, last Sunday the USDA rated this year’s Iowa corn crop as 54 percent in ‘Good’ to ‘Excellent’ condition and 15 percent is ‘Poor’ or ‘Very Poor.’ Last year 72 percent was rated ‘Good’ to ‘Excellent’ and 5 percent was in ‘Poor’ or ‘Very Poor’ condition during the same week. Average plant height as of Sunday was 24 inches compared to 40 inches at end of the same week last year.Growing Degree Days continue to lag behind normal all over the state

The Importance of Play in Early Childhood Education

Play is “work” for young children and is understood to build necessary language and social skills and understanding. This thesis project, an analytic review, explores the subject of play within the early childhood classroom environment while considering both cognitive constructivism and social constructivism through the lens of Piaget and Vygotsky. The multiple purposes of the review were to gain a more complete understanding of the functions of play in the early childhood setting, emphasize the importance of play for children\u27s intellectual, emotional and social growth, and to analyze a body of knowledge of developmental and cognitive theories pertaining to play in order to establish a basis for making decisions regarding the place of play in early childhood environments

The forgotten girls: the state of evidence for health interventions for pregnant adolescents and their newborns in low-income and middle-income countries

Every year, an estimated 21 million girls aged 15–19 years become pregnant in low-income and middle-income countries (LMICs). Policy responses have focused on reducing the adolescent birth rate whereas efforts to support pregnant adolescents have developed more slowly. We did a systematic review of interventions addressing any health-related outcome for pregnant adolescents and their newborn babies in LMICs and mapped its results to a framework describing high-quality health systems for pregnant adolescents. Although we identified some promising interventions, such as micronutrient supplementation, conditional cash transfers, and well facilitated group care, most studies were at high risk of bias and there were substantial gaps in evidence. These included major gaps in delivery, abortion, and postnatal care, and mental health, violence, and substance misuse-related outcomes. We recommend that the fields of adolescent, maternal, and sexual and reproductive health collaborate to develop more adolescent-inclusive maternal health care and research, and specific interventions for pregnant adolescents. We outline steps to develop high-quality, evidence-based care for the millions of pregnant adolescents and their newborns who currently do not receive this

A lifetime’s adventure in extracellular K+ regulation: the Scottish connection

In a career that has spanned 45 years and shows no signs of slowing down, Dr Bruce Ransom has devoted considerable time and energy to studying regulation of interstitial K+. When Bruce commenced his studies in 1969 virtually nothing was known of the functions of glial cells, but Bruce’s research contributed to the physiological assignation of function to mammalian astrocytes, namely interstitial K+ buffering. The experiments that I describe in this review concern the response of the membrane potential (Em) of in vivo cat cortical astrocytes to changes in [K+]o, an experimental manoeuvre that was achieved in two different ways. The first involved recording the Em of an astrocyte while the initial aCSF was switched to one with different K+, whereas in the second series of experiments the cortex was stimulated and the response of the astrocyte Em to the K+ released from neighbouring neurons was recorded. The astrocytes responded in a qualitatively predictable manner, but quantitatively the changes were not as predicted by the Nernst equation. Elevations in interstitial K+ are not sustained and K+ returns to baseline rapidly due to the buffering capacity of astrocytes, a phenomenon studied by Bruce, and his son Chris, published 27 years after Bruce’s initial publications. Thus, a lifetime spent investigating K+ buffering has seen enormous advances in glial research, from the time cells were identified as ‘presumed’ glial cells or ‘silent cells’, to the present day, where glial cells are recognised as contributing to every important physiological brain function

Winter Rye Cover Crop Biomass Production, Degradation, and Nitrogen Recycling

Winter rye (Secale cereale L.) cover crop (RCC) use in corn (Zea mays L.) and soybean [Glycine max. (L.) Merr.] production can alter N dynamics compared to no RCC. The objectives of this study were to evaluate RCC biomass production (BP) and subsequent RCC degradation (BD) and N recycling in a no-till corn–soybean (CS) rotation. Aboveground RCC was sampled at spring termination for biomass dry matter (DM), C, and N. To evaluate BD and remaining C and N, RCC biomass was put into nylon mesh bags, placed on the soil surface, and collected multiple times over 105 d. Treatments included rye cover crop following soybean (RCC-FS) and corn (RCC-FC), and prior-year N applied to corn. Overall, the RCC BP and N was low due to low soil profile NO3–N. Across sites and years, the greatest BP was with RCC-FC that received 225 kg N ha–1 (1280 kg DM ha–1), with similar N uptake as with RCC-FS (27 kg N ha–1). The RCC biomass and N remaining decreased over time following an exponential decay. An average 62% biomass with RCC-FS and RCC-FC degraded after 105 d; however, N recycled was greater with RCC-FS than RCC-FC [22 (80%) vs. 14 (64%) kg N ha–1, respectively], and was influenced by the RCC C/N ratio. The RCC did not recycle an agronomically meaningful amount of N, which limited N that could potentially be supplied to corn. Rye cover crops can conserve soil N, and with improved management and growth, recycling of crop-available N should increase