Effect of Defoliation at Different Stages on Grain Sorghum

Loss of leaf area usually results in yield loss in grain crops, but the amount of yield loss varies with extent and timing of defoliation. Grass crops, such as corn and grain sorghum, are particularly sensitive to leaf area loss near the time of seed set because there is little opportunity for the plant to compensate. An experiment to quantify yield reductions associated with various levels of defoliation imposed at different stages of grain sorghum development was conducted at Manhattan, KS, in 2022. Target defoli­ations of 0, 33, 66, and 100% were imposed at 5-leaf, flag-leaf-appearance, half-bloom, and hard-dough stages. Defoliation of 5-leaf sorghum resulted in minimal yield loss unless the defoliation rate was 100%, which delayed heading and reduced head size and seed size. Leaf area losses of 50% or more at the hard dough stage caused yield reduc­tions of only about 10–12%. Yield reductions were greatest when leaf area was lost at flag leaf appearance or half bloom. Leaf area loss of 60% and 100% caused yield losses of 25% and 75%, respectively. These yield losses were associated with different combina­tions of reductions in head size and seed size

Effect of Late Planting Dates on Corn Yield

Planting date studies have been conducted for corn over many years. Often the focus has been to determine the optimum planting date for maximizing yield. In some areas, planting early-maturing corn hybrids as early as possible has been a successful strategy for avoiding hot, dry conditions at the critical pollination and early grain fill stages. Planting later can be an alternative strategy that attempts to avoid the most intense heat by moving the critical growth stages for corn centered around pollination to later in the growing season. This strategy has been adopted by some growers in areas that often encounter heat and moisture stress during the growing season. However, crop insur­ance cutoff dates for planting are earlier than some farmers may want to plant their corn acres. The purpose of these studies was to assess the yield potential for corn planted after the insurance planting cutoff date and to compare corn yields from a wide range of planting dates

Long-Term Cover Crop Management Effects on Soil Health in Semiarid Dryland Cropping Systems

Growing cover crops (CC) in semiarid drylands may provide benefits to soil health. This study examined long-term CC management effects in a no-till winter wheat-grain sorghum-fallow cropping system in southwest Kansas. Objectives were to assess the impacts of CCs on 1) soil organic carbon (SOC) and nitrogen (N) stocks, 2) soil susceptibility to erosion, as well as to 3) quantify the effects of haying cover crops as annual forages. Treatments were spring-planted and included peas for grain as well as one-, three-, and six-species CC mixtures of oats, triticale, peas, buckwheat, turnips, and radishes compared with conventional chemical-fallow. Half of each CC treatment was harvested for forage. All phases of each rotation were present every year. Soil samples were collected from the 0- to 6-inch depth in 2018 and 2019 corresponding with wheat planting and harvest in the three-year rotation. Results indicate no significant difference in SOC with CCs compared to fallow in either 2018 or 2019, though SOC stocks were greater than in 2012. This was possibly due to periods of drought reducing total carbon (C) inputs compared to earlier periods of relatively greater precipitation. Haying of CCs had no effect on soil health indicators compared to when CCs were left standing. Soil N was not increased with CCs compared to fallow or peas. Mean weight diameter of wet aggregates in 2018 was not different between CCs hayed (0.042 in.) and CCs left standing (0.044 in.) but were greater than fallow (0.033 in.) or peas (0.030 in.). Growing a CC significantly increased the proportion of larger (0.30- to 0.08-in.) aggregates (37%) compared to peas (21%) but not compared to fallow (24%). These differences were not significant after wheat harvest in 2019. Our findings suggest that CCs may improve soil physical properties compared to conventional chem-fallow in semiarid dryland cropping systems

Harvest Method, Cultivar, and Time of Swathing Effects on Yield and Oil Content of Winter Canola

Producers want to achieve the highest yield and oil content possible using either swathing or direct cutting to harvest winter canola. Multi-year experiments were conducted to evaluate the effects of harvest method (swathing versus direct cutting) and cultivar on seed moisture, yield, and oil content; and to evaluate the effects of swathing timing on yield and oil content. The harvest method experiments were conducted for two seasons at the Redd Foundation Field near Partridge, KS. The time of swathing experiments were conducted for two seasons near Manhattan, KS. In 2016 and 2017, harvest method had a significant effect on seed moisture, yield, and oil content. Swathing produced seed with lower moisture content and greater yield, but direct cutting produced seed with the highest oil content. Cultivars differed in their response to yield depending on the harvest method used. Some cultivars responded positively to swathing, others responded positively to direct cutting, and some showed no response to harvest method. Time of swathing had a significant effect on yield and oil content. As a rule, as seed color change progressed, yield and oil content increased. All swathing treatments had greater yield than direct cutting except when swathing was done at green seed. Seed from direct cutting had significantly greater oil content than seed from all swathing treatments. Both swathing and direct cutting can be used effec­tively to harvest winter canola

Forage Accumulation of Spring and Summer Cover Crops in Western Kansas

Intensification of no-till dryland cropping systems in western Kansas with cover crops (CCs) may provide important ecosystem services while also supplying annual forage for livestock. Two experiments were initiated in 2015 and 2016 near Brownell, KS, to determine the forage production potential of spring and summer CCs in a winter wheat-grain sorghum-fallow crop rotation. Cover crops were mechanically harvested as hayed forage to a height of 6 inches or mob-grazed with yearling heifers (weighing approximately 1000 lb each) stocked at 3 head/acre/day. Forage accumulation was determined for the hayed treatment using a small plot forage harvester, and samples of the grazed treatment were hand-clipped before and after grazing every year from 2015 to 2020. Results showed forage accumulation of spring CCs grown in place of fallow following grain sorghum averaged 2231 lb/a dry forage mass and ranged from 1427 to 2871 lb/a. Similarly, forage accumulation of summer CCs planted after wheat harvest averaged 2513 lb/a dry forage mass and ranged from 956 to 3718 lb/a. In 2017, summer CCs failed to produce a harvestable yield. Results suggest that CCs may provide desirable annual forage for livestock. However, forage accumulation of both spring and summer CCs was variable in this study. In years that spring CCs were planted early (before March 15), yields tended to be higher (\u3e2200 lb/a) due to less susceptibility to heat and moisture stress. Summer CCs performed best when planted immediately following wheat harvest to take advantage of summer rains and to produce as much forage mass (\u3e3000 lb/a in favorable years) as possible before the first killing frost or about October 15 for most of western Kansas

Spring and Summer Cover Crop Effects on Dryland Wheat and Grain Sorghum Yields in Western Kansas

Incorporating cover crops (CC) to replace fallow in traditional dryland cropping systems in the semi-arid conditions of western Kansas has the potential to enhance soil health, suppress weeds, and increase precipitation use efficiency. The returns from haying or grazing can help cover costs of CC establishment and any reduction in yield from the subsequent grain crop. Two studies were initiated in 2015 and 2016 near Brownell, KS, to investigate dual-purpose spring and summer CC management effects on subsequent grain yields in a three-year no-till (NT) dryland winter wheat-grain sorghum-fallow cropping system. Cover crops were planted in early spring between grain sorghum and winter wheat or in mid-summer soon after wheat harvest. Cover crops were grazed with yearling heifers, hayed at a six-inch stubble height, or left standing (no forage removal). All CC treatments were compared to NT fallow with no CC. Results showed spring CCs reduced wheat yields between 25 and 31% compared to fallow (59 bu/a) in two of three years, with no difference in the other year. Wheat yields were not different among CC management strategies. Summer CCs reduced grain sorghum yields at rates up to 39% compared to fallow (67 bu/a) in one of three years only when CCs were grazed or left standing but not when CCs were hayed. Sorghum yields were not different in the other two years. Yields of wheat or grain sorghum grown more than one year following CCs in the crop rotation were unaffected by CC treatments. These results showed CCs reduced subsequent crop yields compared to fallow. However, grazed or hayed CCs had no negative effects on dryland wheat and grain sorghum yields compared to standing CCs. Allowing grazing or haying of CCs on land enrolled in Natural Resources Conservation Service cost-share programs could increase producer adoption of CCs in semi-arid western Kansas to enhance regional soil health and increase dryland cropping system profitability

Dual-Purpose Cover Crop Effects on Soil Health in Western Kansas No-Till Dryland Cropping

Increasing interest in soil health has led producers in western Kansas to consider cover crops (CCs) for increased soil cover and improved soil properties. However, grain yield reductions following CCs in dryland cropping systems necessitate dual-purpose forage harvest to balance goals of environmental and economic sustainability. This study was initiated in 2015 near Brownell, KS, to investigate the effects of dual-purpose CC management in place of fallow on selected soil chemical and physical properties in a no-till winter wheat-grain sorghum-fallow cropping system. Mixed oat and triticale cover crops were either mechanically harvested as hayed forage to a height of 6 inches, mob-grazed with yearling heifers (weighing approximately 1000 lb each) stocked at 3 head/acre/day, or left standing (unharvested). Cover crop treatments were compared to chemically-controlled no-till fallow. Soil samples were collected following CC termination, but before winter wheat planting in 2019 and 2020. Results indicate that dual-purpose CCs had no effect on soil bulk density or porosity relative to unharvested CCs or the fallow treatment. Soil organic carbon was similar for standing and grazed CCs though carbon stocks were less for the hayed treatment. All CC treatments were similar to fallow. Indicators of soil structure—including mean weight diameter and large macroaggregates—were greater, while small macroaggregates were less for all CCs compared to fallow. These results suggest that dual-purpose CCs in no-till dryland cropping may replace fallow to provide forage for livestock while improving soil health. Still, careful management will be necessary to ensure adequate CC residues are retained such that, when CC growth is limited, grazing of CCs may be more desirable than haying in order to maintain soil properties

Cover Crop Grazing Effects on Soil Compaction Indicators in Western and Central Kansas

Grazing cover crops (CCs) on no-till (NT) croplands in western and central Kansas could increase the profitability of crop production in these water-limited environments. However, little information exists about potential soil compaction associated with grazing CCs in these cropping systems. From 2019 to 2021, two studies investigated the effects of grazing CCs on soil bulk density and penetration resistance in NT cropping systems. At the Kansas State University HB Ranch near Brownell, KS, CCs grazed with yearling heifers were compared to ungrazed CCs and fallow under NT or occasional tillage (OT). In another study, CCs grazed with yearlings or cow-calf pairs were compared to ungrazed CCs across seven site-years on producer fields in western Kansas (Alexander and Hays) and central Kansas (Marquette 1 and 2). Soil bulk density and penetration resistance measurements were made at the time of subsequent grain crop planting following CCs. At Brownell, CC management, tillage, and their interaction had no significant effect (P \u3e 0.05) on soil bulk density. Across years, bulk densities with fallow, ungrazed CCs, and grazed CCs were 1.11, 1.15, and 1.15 g/cm3 at the 0- to 2-inch soil depth, respectively. Soil bulk densities with NT and OT were 1.14 and 1.14 g/cm3 at the 0- to 2-inch soil depth, respectively. Similarly, CC grazing had no significant effect on soil bulk density and penetration resistance across the seven on-farm sites-years. At the western Kansas locations, soil bulk density averaged 1.23 g/cm3 at the 0- to 2-inch soil depth with grazed or ungrazed CCs. At the central Kansas locations, soil bulk density averaged 1.31 and 1.36 g/cm3 at the 0- to 2-inch soil depth for grazed and ungrazed CCs, respectively. Bulk density measured at 2- to 6-inch depth was not different between grazed and ungrazed CC in either study. At Alexander, penetration resistance was 0.52 and 0.52 MPa with grazed and ungrazed CCs, respectively. Penetration resistance was 0.36 and 0.34 MPa with grazed and ungrazed CCs, respectively, at Marquette 1. Results showed that grazing CCs never increased soil bulk density or penetration resistance compared to ungrazed CCs. Based on these findings, grazing CCs on NT fields can be a strategy for producers to balance profitability and soil health

Effect of soil treatments and amendments on the nematode community under miscanthus growing in a lead contaminated military site

Applying phytotechnologies with energy crops on lands contaminated with trace elements provides cellulosic biomass and improves soil health. The process can be reflected in changes in the soil nematode community structure. This study assessed the nematode community composition of soil with Miscanthus grown with different agronomic practices. The research was onducted at Fort Riley, Kansas, USA, in soil with aged contamination by Pb at 1000 to 1500 mg/kg. The experimental design was a randomized complete block composed of four replications of five treatments: Control-undisturbed mixed plant cover and four conditions of Miscanthus growth,which consisted of No-till, Till (immediately before planting), Till + P, and Till + biosolids. Analysis of abundance, diversity, and community functional status indicators showed di�erential sensitivity of nematode taxa to agronomic treatments. Significant transformations in the nematode trophic group structure occurred under Miscanthus cultivation compared with the undisturbed mixed plant cover. Shannon and Pielou index response to agronomic treatments illustrated decreasing nematode community diversity with all Miscanthus agronomic conditions. However, agronomic practices led to increasing nematode community maturity, but those e�ects varied between spring and fall seasons. Increasing herbivores and omnivore-predators were the primary drivers of the observed changes in the nematode community due to planting Miscanthus. The nematode ecological structure indicators suggested that growth in Pb-contaminated land using different agronomical practices likely affects essential soil processes. More study is needed to define the effects of pre-plant tillage and amendments to soil nematode communities and Miscanthus yield over multiple growing seasons of this perennial crop

Soil Microbial Seasonal Community Dynamics in Response to Cover Crop and Phosphorus Fertilizer Usage in a No-Till Corn-Soybean System in 2018

This study examined microorganism community composition in plots managed with and without cover crops and three contrasting phosphorous (P) fertilizer manage­ment techniques in a no-till corn-soybean system. This work was performed in the spring and fall of 2018 at the Kansas Agricultural Watershed Field Laboratory (KAW), Manhattan, KS. The study design was a 2 × 3 complete block factorial design with three replications, with cover crop presence or absence and three levels of P fertilizer management (control, fall broadcast, and spring injected). To examine microorganism community composition, phospholipid fatty acid (PLFA) analysis was used. Only the main effect of cover crop was found to have a significant impact. Results show greater microbial biomass within plots that had a cover crop as compared to those that did not. The community structure between cover crop plots and non-cover crop plots was similar; however, their abundance was less in non-cover crop plots than in those that had a cover crop