Core Ideas Legumes improved N supply for sweet potato grown subsequently. Mucuna aterrima supply more N to sweet potato than other cover crops. Previous legume cultivation reduces 35.2% the mineral N rate on sweet potato. Higher mineral N rate increased growth of sweet potato vines. Selected cover crops can provide N to sweet potato (Ipomoea batatas [L.] Lam) crops cultivated in succession and reduce the need for mineral N application. This study was conducted to determine the growth, leaf N concentration, N uptake, N removal, storage root yield, and N‐use efficiency of sweet potato crop in response to different cover crop sources and mineral N fertilizer rates. A field experiment was performed over 2 agricultural yr using a randomized complete block design with split‐plots and four replications. Whole plots consisted of four cover crops: One control (spontaneous weeds), two legumes (Crotalaria spectabilis and Mucuna aterrima), and one cereal (Pennisetum glaucum). Subplots consisted of four N rates (0, 50, 100, and 200 kg ha−1) applied to the sweet potato. When no N was applied, M. aterrima supplied more N to sweet potato grown in succession but had the same effect as C. spectabilis on root yield. P. glaucum and spontaneous weeds had the same effect on the N supply and performance of sweet potato. The N rates for the optimum root yield of sweet potato were 49.6 and 76.6 kg N ha−1 when grown after legume and non‐legume species. In tropical conditions, the use of legumes as cover crops reduced the need for mineral N fertilizers by up to 35.2% for sweet potato. The cultivation history of a field should be an important consideration when determining the N fertilization for sweet potato because a high N supply favored the growth of vegetative plant parts.

Improper or suboptimal application techniques can cause decreased weed control and increased environmental contamination. Droplet size is a key factor in pesticide applications in regard to both drift and efficacy. Droplet size can be altered by several application parameters, such as nozzle type, pressure, orifice size, and spray solution. The objective of this study was to evaluate the influence of nozzle type, application speed, and pressure when using glyphosate, dicamba, or glyphosate plus dicamba on droplet size and control of common lambsquarters, velvetleaf, kochia, and grain sorghum. The study was conducted with two herbicides, glyphosate at 0.77 kg ae ha−1 and dicamba at 0.56 kg ae ha−1, tested alone and in combination. The application rate was 94 L ha−1 at three different speeds (8, 16, and 24 kph), and the pressures used were low, medium, and high for each speed and orifice size combination. The pressures were combined with the appropriate orifice size to deliver a fixed spray volume. An XR, AIXR, and TTI nozzle were used (two of which are venturi nozzle designs). The droplet size ranged from 219 to 232 µm for the XR nozzle across the three solutions, 440 to 482 µm for the AIXR nozzle, and 740 to 828 µm for the TTI nozzle. Solutions using dicamba resulted in the largest droplet size, followed by glyphosate and then the combination. There were no significant interactions for nozzle × herbicide across all species.