Summer weeds including established bermudagrass and nutsedge are of economic concern to alfalfa growers in western Arizona. Two replicated evaluations of norflurazon herbicide applications for summer weed control were conducted on established alfalfa fields in La Paz County. Zorial Rapid 80 WP and Evital 5G herbicides were tested for their effectiveness of bermudagrass and nutsedge control when applied following hay harvest but prior to irrigation in early spring. Zorial 80 WP was applied at 2.0 lb a. i. /acre. Evital 5G was applied at single application rates of 1.5, 2.0, and 3.0 lb a. i. /acre in spring and two split applications in spring and summer for a total of 2.0, 3.0, and 4.0 lb a. i. /acre. Norflurazon applications resulted in bleaching and shoot tip death of established bermudagrass 49 days after a single application (DAT), however by 78 DAT bermudagrass regrowth reinfested all plots resulting in zero control. Purple nutsedge control resulting from a single application of Evital 5G at 2.0 lb a.i./acre was 41, 82, and 35% at 35, 63, and 99 DAT, respectively. However, Zorial 80 WP applied at 2.0 lb a. i. /acre provided only 5, 23, and 0% purple nutsedge control at 35, 63, and 99 DAT, respectively. The limited effectiveness of the Zorial 80 WP spray solution for nutsedge control resulted from poor soil incorporation since the liquid was unable to penetrate the dense nutsedge foliage. The Evital 5G norflurazon formulation provided promising purple nutsedge control following one application to established alfalfa since the weight of the granules allowed the herbicide to reach the soil surface where irrigation could move the herbicide down through the soil profile to nutsedge roots. At 99 DAT a second split Evital treatment was applied to control nutsedge regrowth, and hopefully provide season long control. Nutsedge control results following this second split application are pending.

Plant growth regulators were aerially applied on April 26, 1996, to two alfalfa fields, one (Cibola) in its first year of production and the other field (CUF 101) in its third year. The first year field was approximately 50% through the cutting cycle and the third year field was approximately 30% through the cutting cycle when applications were made. No statistical differences were noted in hay tonnage the first cutting after application. Yield increases due to treatments were noted in the second cutting and maximum increases ranged from 277 -461 lbs of hay per acre. No yield or quality differences were noted the third cutting after application. The two fields differed in their response. The lowest rates of plant growth regulators produced higher yields in the first year field, but these treatment rates had greatly lowered hay quality the previous cutting. These effects were not noticed in the third year stand field. Increased hay tonnage was noted in the third year field from the 16 oz/acre rates, but was not evident in the first year field. Hay quality was usually highest in the check the first two cuttings after treatment. It is unknown if the differences noted between the two fields are due to different age of plants, variety and/or stage of growth when treatments were applied.

Some growers feel that nitrogen (N) fixing nodules found on the roots of the alfalfa plant are ineffective in cold soil during the winter and early spring. Thus, starter N fertilizer is commonly applied in late winter to established alfalfa to enhance growth until spring when the soil warms up and alfalfa begins actively fixing atmospheric N₂. Established alfalfa normally does not benefit from applications of N fertilizer since it is a leguminous crop that is capable of fixing its own N from atmospheric N₂. Afield experiment was conducted to determine the effect of N fertilizer applied in winter on alfalfa hay yield at the first cutting in spring. Two treatments consisted of an unfertilized check plot and UAN 32 water run at a rate of 35 lbs. N/acre to three year old 'CVF 101' alfalfa grown on a silt loam soil testing deficient in nitrate-N. Maximum alfalfa hay yield (J ton/acre) was obtained at the first spring cutting without N fertilizer application. However, since the field has a known yield potential of 1.5 ton/acre, factors other than fertility influenced the alfalfa hay yields observed in this study.

No description available.

Inaug.-Diss.--Geologie--Ruprecht-Karls-Universität Heidelberg, 1992. / Bibliogr. p. 152-157.

Common integrated vegetation management (IVM) practices including herbicide and mowing applications on right-of-ways and forages were evaluated on green antelopehorn populations near Starkville, MS. Live stems in each plot were counted prior to treatment application and approximately one year after treatment (YAT). Analysis of the stem counts 1YAT indicated aminopyralid+metsulfuron, imazapyr, picloram+2,4-D, maximum rates of triclopyr ester or choline, glyphosate, imazapyr+aminocyclopyrachlor+metsulfuron reduced the number of green antelopehorn stems compared to the untreated. Aminocyclopyrachlor, aminocyclopyrachlor+chlorsulfuron, aminopyralid, aminopyralid+2,4-D, dicamba+2,4-D, foramsulfuron+iodosulfuron+thiencarbazone, fluroxypyr, hexazinone, metsulfuron, metsulfuron+chlorsulfuron, nicosulfuron+metsulfuron, sulfometuron, sulfosulfuron or low rates of triclopyr did not reduce the stem count 1YAT when compared to the untreated. Mowing timing and frequencies applications were initiated May through July and evaluated through August. Mowing early in the season increased milkweed stems one month after treatment versus late season mowings. Majority of milkweed plants developed mature seed pods and senesced by early August.

No description available.

Two experiments were conducted to determine the effects of grazing stockpiled perennial forage in field paddocks relative to feeding similar quality round bale hay in drylot pens on rumen degradation characteristics of forage; beef cow performance, cow reproductive efficiency, estimated dry matter intake and forage utilization, forage yield and quality, soil nutrients and system costs. Winter feeding systems were (i) stockpiled perennial forage (TDN = 58.9%; CP = 8.5%) grazing (SPF) and (ii) drylot feeding (DL) of round bale hay (TDN = 57.9%; CP = 8.4%). Experiment I was an in situ study, where five Hereford heifers (398 ± 14 kg) fitted with rumen cannulae were fed a grass hay (DM = 93.2%; TDN = 50.8%; CP = 9.8%; NDF = 66.2%) diet. In situ degradability of both stockpiled forage (SPF) and round bale hay (BH) samples collected at start (October) and end (December) of the field study were determined. The soluble fraction (S) of DM was greater (P = 0.01) in SPF October forage compared to SPF December, BH October and BH December forages. The potentially degradable fraction (D) of CP was lowest (P = 0.04) in BH December forage than in SPF October, SPF December and BH October forages suggesting that hay quality declined more rapidly than stockpiled forage and method of preservation may have affected overall hay quality. Furthermore, D fraction of both ADF and NDF was higher in SPF samples suggesting stockpiled forage may be more digestible than hay. However, the D fraction of NDF in both SPF and BH forages declined with later sampling date possibly due to effect of weathering and leaf loss. In Experiment II, 6, 4-ha paddocks consisting of meadow bromegrass (Bromus riparius Rehm) and alfalfa (Medicago sativa), were randomly assigned to 1 of 2 replicated (n = 3) winter feeding systems. In this study 58 dry pregnant (120 ± 16 d) Angus cows (675 kg ± 51 kg), stratified by body weight (BW; corrected for conceptus gain), were allocated to either the SPF or DL systems. Cows in winter feeding systems were provided additional energy supplement (rolled barley) (TDN = 86.4%; CP = 12.4%) depending on environmental conditions to maintain body condition, with no weight gain above that of conceptus growth. Dry matter intake (DMI) and forage utilization were estimated using the herbage weight disappearance method. The effects of winter feeding systems on soil nutrients were determined the following spring after winter grazing. Forage yield in DL (4683 ± 495 kg ha-1) and SPF (4032 ± 495 kg ha-1) systems was not different (P = 0.18) between treatments. However, forage utilization was lower (P < 0.01) in SPF (83.5%) than the DL (94.4%) system, signifying lower accessibility to stockpiled forage due to snow depth, lower temperatures, freezing rain and wind. Cows in the SPF system had higher forage DMI (P = 0.04) and supplementation intake (P < 0.01) compared to cows in drylot pens likely a combined effect of effective ambient temperatures below the lower critical temperature (LCT) during the grazing period and the higher potentially digestible fraction of neutral detergent fiber in stockpiled forage than hay. Cow BW change, average daily gain, rib fat change and rump fat change were not different (P > 0.05) between winter feeding systems. Reproductive performance of beef cows was not affected (P > 0.05) by either winter feeding methods as cows in both systems maintained body condition score (BCS) at 2.5 to 3.0 throughout the study. Average total production cost was 19% lower in SPF system compared to DL system. In conclusion, the rumen degradation characteristics of stockpiled perennial forages focused in this study support the utilization these forages in a winter feeding system to meet the nutrient requirements of dry beef cows in early to mid-gestation. It may be cost effective to manage beef cows in field grazing of stockpiled perennial forages in western Canada, without any negative impact on beef cow performance or reproductive efficiency.

Farmers in the developing world frequently find themselves in uncertain and risky environments: often having to make decisions based on very little information. Functional models are needed to support farmers tactical decisions. In order to develop an appropriate model, a comparison is carried out of potential modelling approaches to address the question of what to grow where. A probabilistic GlS model is identified in this research as a suitable model for this purpose. This model is implemented as the stand-alone Spatial Decision Support System (SDSS) CaNaSTA, based on trial data and expert knowledge available for Central America and forage crops. The processes and methods used address many of the problems encountered with other agricultural DSS and SDSS. CaNaSTA shows significant overlap with recommendations from other sources. In addition, CaNaSTA provides details on the likely adaptation distribution of each species at each location, as well as measures of sensitivity and certainty. The combination of data and expert knowledge in a spatial environment allows spatial and aspatial uncertainty to be explicitly modelled. This is an original approach to the problem of helping farmers decide what to plant where.

Two common (Piper and Sweet Sudan), four hybrid sudangrass (NK Trudan 8, Cargill HS 35, and Germaine's G 555), and three sorghum-sudangrass hybrid (DK SX 17, TE Haygrazer II, and Pioneer 877F) varieties are currently being evaluated for hay yield and quality at four cuttings in large field plots located at Quail Mesa Farms in southwest La Paz County. Preliminary results from the first two hay cuttings are presented showing that of the nine sudangrass varieties examined in this study, Piper, Cargill HS 35, and NC+ 200 sudangrass varieties had superior hay tonnage and quality. However, we need to determine if this pattern of hay tonnage and quality can be maintained over at least four hay cuttings. The sorghum-sudangrass hybrids produced relatively poor quality hay, and had relatively high prussic acid levels at the second cutting.