Days Remaining to First Killing Frost

Crop producers and extension field staff need to be able to evaluate how much of the growing season remains before a killing frost. The table on the next page lists DAYS TO FREEZE or how many days are remaining, from a specified date, at a given location, to the first killing frost within South Dakota

Characteristics and Seeding Rates of some Crops Grown in South Dakota

Certain seed characteristics relate to seeding rates for various crops you might be planning to plant as alternative crops this year

Mustard Production (yellow, brown and oriental)

General: The most commonly grown mustard in the United States in the yellow mustard. The brown and the oriental are not as frequently seen. Mustards belong to the Cruciferae (mustard) family and the genus Brassica which includes several other crops such as cabbage, broccoli, rape, and turnips. Yellow mustard belong to the species B. hirta; the brown and oriental mustards are in B. juncea which is a hybridization of B. nigra (black mustard) and B. campestris (turnip rape and oilseed rape). Most yellow, brown, and oriental mustards are used either in the production of table mustard or seasoning for processed foods

Nitrate and Prussic Acid: How to Obtain a Representative Sample

If you have drought-stressed crops and still want to use them, there are two options: (1) Bale the crop, or (2) ensile it. In either case, the forage should be evaluated for crop hazards like nitrates or prussic acid (also called hydrocyanic acid, HCN) that are potentially toxic to livestock. Nitrates: Baling will not lower the nitrate levels in a stressed crop once it is cured. In contrast, ensiling generally lowers nitrate levels about 35% once fermentation is complete. To determine nitrate levels in the drought-stressed plants you need a representative sample for testing. To collect a representative field crop sample, define the sample area, determine a sample height, and note the time of day the sample is obtained

Conducting an On-Farm Research Trial in Corn A Paired-Treatment Experiment With Results Analyzed By MS Excel Using The Anova: Two-Factor Without Replication Option

This guide will discuss and illustrate a possible scenario for conducting an effective on-farm research trial using paired-treatments in corn. Possible treatments comparisons might include: current vs. new hybrid, no starter vs. starter fertilizer, soil-incorporated vs. post-emergence applications, and before vs. after treatments. Treatments do not have to be applied at the same time or stage; one treatment might be applied early while the second is applied late

Changing Corn Hybrids or Soybean Varieties When Seeding Is Delayed

Inclement weather during the corn and soybean planting season causes many growers to inquire about changing corn hybrids and soybean varieties as a result of delayed seeding. Growers should not change maturities until seeding is delayed to late Maye for corn and early June for soybeans

Safflower Production Tips

The 1990 Farm Bill has designed safflower as a minor oilseed crop which is permitted on “flex” and 0/92 acres. This publication describes the agronomic characteristics of safflower

Emergency Late-Seeding Options

This document provides an outline of the latest in which farmers can plant crops such as rowcrops, alternative crops, and forage crops

Planetary nebulae after common-envelope phases initiated by low-mass red giants

It is likely that at least some planetary nebulae are composed of matter which was ejected from a binary star system during common-envelope (CE) evolution. For these planetary nebulae the ionizing component is the hot and luminous remnant of a giant which had its envelope ejected by a companion in the process of spiralling-in to its current short-period orbit. A large fraction of CE phases which end with ejection of the envelope are thought to be initiated by low-mass red giants, giants with inert, degenerate helium cores. We discuss the possible end-of-CE structures of such stars and their subsequent evolution to investigate for which structures planetary nebulae are formed. We assume that a planetary nebula forms if the remnant reaches an effective temperature greater than 30 kK within 10^4 yr of ejecting its envelope. We assume that the composition profile is unchanged during the CE phase so that possible remnant structures are parametrized by the end-of-CE core mass, envelope mass and entropy profile. We find that planetary nebulae are expected in post-CE systems with core masses greater than about 0.3 solar masses if remnants end the CE phase in thermal equilibrium. We show that whether the remnant undergoes a pre-white dwarf plateau phase depends on the prescribed end-of-CE envelope mass. Thus, observing a young post-CE system would constrain the end-of CE envelope mass and post-CE evolution.Comment: Published in MNRAS. 12 pages, 12 figures. Minor changes to match published versio

Takeoff/approach noise for a model counterrotation propeller with a forward-swept upstream rotor

A scale model of a counterrotating propeller with forward-swept blades in the forward rotor and aft-swept blades in the aft rotor (designated F39/A31) has been tested in the NASA Lewis 9- by 15-Foot Anechoic Wind Tunnel. This paper presents aeroacoustic results at a takeoff/approach condition of Mach 0.20. Laser Doppler velocimeter results taken in a plane between the two rotors are also included to quantify the interaction flow field. The intention of the forward-swept design is to reduce the magnitude of the forward rotor tip vortex and/or wakes which impinge on the aft rotor, thus lowering the interaction tone levels. A reference model propeller (designated F31/A31), having aft-swept blades in both rotors, was also tested. Aeroelastic performance of the F39/A31 propeller was disappointing. The forward rotor tip region tended to untwist toward higher effective blade angles under load. The forward rotor also exhibited steady state blade flutter at speeds and loadings well below the design condition. The noise results, based on sideline acoustic data, show that the interaction tone levels were up to 8 dB higher with the forward-swept design compared to those for the reference propeller at similar operating conditions, with these tone level differences extending down to lower propeller speeds where flutter did not occur. These acoustic results are for a poorly-performing forward-swept propeller. It is quite possible that a properly-designed forward-swept propeller would exhibit substantial interaction tone level reductions