Palmer Amaranth (Amaranthus palmeri) Control in Postharvest Wheat Stubble in the Central Great Plains

Late-season control of Palmer amaranth in postharvest wheat stubble is important for reducing the seedbank. Our objectives were to evaluate the efficacy of late-season POST herbicides for Palmer amaranth control, shoot dry biomass and seed production in postharvest wheat stubble. Field experiments were conducted at Kansas State University Agricultural Research Center near Hays, KS during 2019 and 2020 growing seasons. The study site had a natural seedbank of Palmer amaranth. Herbicide treatments were applied 3 wk after wheat harvest when Palmer amaranth plants had reached inflorescence initiation stage. Palmer amaranth was controlled 96 to 98% 8 weeks after treatment and shoot biomass as well as seed production was prevented when paraquat was applied alone or when mixed with atrazine, metribuzin, flumioxazin, 2,4-D, sulfentrazone, pyroxasulfone + sulfentrazone, or flumioxazin + metribuzin, and with glyphosate + dicamba, glyphosate + 2,4-D, saflufenacil + 2,4-D, glufosinate + dicamba + glyphosate, and glufosinate + 2,4-D + glyphosate. Palmer amaranth was controlled 89 to 93% with application of glyphosate, glufosinate, dicamba + 2,4-D, saflufenacil + atrazine, and saflufenacil + metribuzin resulting in Palmer amaranth shoot biomass of 15 to 56 g m -2 and production of 1,080 to 7,040 seeds m−2. Palmer amaranth control was less than 86% with application of dicamba, 2,4-D, dicamba + atrazine, and saflufenacil resulting in Palmer amaranth shoot biomass of 38 to 47 g m−2 and production of 3,110 to 6,190 seeds m−2. Palmer amaranth was controlled 63 and 72%, shoot biomass was 178 and 161 g m−2 and seed production was 35,180 and 39,510 seeds m−2, respectively, with application of 2,4-D + bromoxynil + fluroxypyr, and bromoxynil + pyrasulfotole + atrazine. Growers should utilize these effective POST herbicide mixes for Palmer amaranth control to prevent seed prevention postharvest in wheat stubble.

Application of Dairy Manure Amended with Mineral Fertilizer on Stubble-Covered Soil: Effects on Ammonia Emissions

The reduction in the manure application rates through enrichment with mineral fertilizer has the potential to reduce costs, decrease environmental pollution, and extend the manure benefits to greater acreage. A pot experiment was carried out to assess ammonia emissions from dairy manure amended with mineral fertilizers applied on wheat stubble. The treatments were: control (no fertilization), urea (U), calcium ammonium nitrate (AN), dairy manure (MAN), urea + dairy manure (UMAN), and calcium ammonium nitrate + dairy manure (ANMAN). A dynamic chamber system was used to measure NH3 emissions during seven days after soil application. UMAN and ANMAN treatments led to higher NH3 emissions than each isolated component. This might be motivated by the manure pH. Thus, the enrichment of dairy manure with U or AN for application on stubble-covered soil should not be recommended. Nevertheless, some manure pre-treatments, such as acidification, or the use of other mineral fertilizers might improve such solution.

Agrotechnical and Energy Performance of Tillage Tools

Introduction. One of the areas of agricultural production is crop production. At the same time, it is necessary to take into account all available possibilities of reducing the energy consumption and labor required for tillage operations that can be achieved by using energy efficient tillage tools. Materials and Methods. In the course of the research, an agrotechnical and energy assessment of the technological process of soil cultivation performed by tillage tools was carried out. The agrotechnical assessment includes identifying the indicators of unevenness of the tillage tool travel depth, soil pulverization, ridging, and the content of erosion threatening particles. As an energy assessment, the indicator of draught created by a tillage tool was taken. The researches were carried out for various configurations of the chisel cultivators with flat and curved hoes, and elements made of polymer. Results. The data of agricultural assessment and draught of chisel cultivators were obtained for various agricultural backgrounds: winter wheat stubble with preliminary disking in one track, winter barley stubble with preliminary disking in one track, and autumn fallow on the background. Discussion and Conclusion. According to the results of the research, it was found that, in terms of quality indicators, the tillage tools meet the agrotechnical requirements for a given processing depth of 25–35 cm. The operation of the chisel equipped with a curved hoe is characterized by the highest presence of clods up to 5 cm (91–96%). The ridge height was 6.8–8.0 cm for all tillage tools. It has been established that the tillage tools are advisable to be uses for anti-erosion soil cultivation. In terms of preserving plant and crop residues, a chisel with a curved hoe providing their content by 9.5–28.6% more than with a polymer of 13.2–14.3%. The chisel with polymer has the smallest draught of 7.6 kN, which is 18.28% lower in comparison with tillage tools equipped with a flat hoe.

A LiDAR Sensor-Based Spray Boom Height Detection Method and the Corresponding Experimental Validation

Sprayer boom height (Hb) variations affect the deposition and distribution of droplets. An Hb control system is used to adjust Hb to maintain an optimum distance between the boom and the crop canopy, and an Hb detection sensor is a key component of the Hb control system. This study presents a new, low-cost light detection and ranging (LiDAR) sensor for Hb detection developed based on the principle of single-point ranging. To examine the detection performance of the LiDAR sensor, a step height detection experiment, a field ground detection experiment, and a wheat stubble (WS) height detection experiment as well as a comparison with an ultrasonic sensor were performed. The results showed that the LiDAR sensor could be used to detect Hb. When used to detect the WS height (HWS), the LiDAR sensor primarily detected the WS roots and the inside of the WS canopy. HWS and movement speed of the LiDAR sensor (VLiDAR) has a greater impact on the detection performance of the LiDAR sensor for the WS canopy than that for the WS roots. The detection error of the LiDAR sensor for the WS roots is less than 5.00%, and the detection error of the LiDAR sensor for the WS canopy is greater than 8.00%. The detection value from the LiDAR sensor to the WS root multiplied by 1.05 can be used as a reference basis for adjusting Hb, and after the WS canopy height is added to the basis, the value can be used as an index for adjusting Hb in WS field spraying. The results of this study will promote research on the boom height detection method and autonomous Hb control system.

Herbicide Spray Deposition in Wheat Stubble as Affected by Nozzle Type and Application Direction

Tall wheat (Triticum aestivum L.) stubble can enhance soil water conservation during the fallow-period by trapping snow and decreasing evaporation. However, standing wheat stubble can intercept herbicide spray droplets before they reach their intended targets. This experiment aimed to evaluate the effects of three wheat stubble heights (>70 cm, 35 cm, and no-stubble), four nozzle types (XR, TTJ, AIXR, and TTI), and three application directions (angular (45°), perpendicular (90°), and parallel (0°) to the wheat row) on a spray deposition of glyphosate and a dicamba tank mixture. The ranking of droplet size from smallest to largest based on volume median diameter (VMD) was XR, TTJ, AIXR, and TTI. Wheat stubble greater than 70 cm decreased spray deposition 37%, while 35 cm stubble caused a 23% decrease. Sprayer application directions and nozzle type had significant interaction on spray deposition. Perpendicular application direction decreased spray deposition relative to the angular application direction for TTJ and TTI. Parallel application direction had lower spray deposition than angular application direction for TTJ and XR. Similarly, relatively-high-spray deposition (~75%) was provided by angular application direction regardless of the nozzle type. Applicators should consider traveling in an angular direction to the wheat rows for improved droplet deposition across spray nozzle types.