The study was based on the analysis of data obtained from long-term field experiments on nitrogen fertilization conducted in IUNG experimental stations in the nineties. Cereal crops were grown in 4-field crop rotation: winter cereal after rapeseed and spring ones after root crops. The relationship between nitrogen content and dry matter accumulation in winter and spring wheat, winter triticale and spring barley was described by the equation. It was stated that for optimally nutrished with nitrogen winter and spring wheat and winter triticale coefficients were very similar

Experiments with a view to establishing the biological value of different preceding crops such as clover, lucerne, vetch-oats mixture for winter wheat and their influence as well as the influence of green manure on the yield and it's quality were carried out at the Joniskelis Research Station over the period 1996-1998 on a heavy loam soil. Results of the trials showed that lucerne and clover left the largest amount of plant residues and nutrients, winter wheat as a preceding crop left in soil the smallest amount of residues with a low content of nutriet. The highest yield of winter wheat was obtained after lucerne, and the lowest after vetch-oats mixture. In general, the yields were posityvely affected by soil manuring. The amount of crude proteins in grains of winter wheat was under the influence of nitrogen content in preceding crop residues and manure

The reaction of winter wheat varieties on herbicides was estimated in 1996-98. The unfavourable weather in winter caused decrease of yielding of winter wheat varieties Aleta and Jubilatka after applied in autumn of Affinity 50,75 EG. The same situation after applied post emergence in autumn of Dicuran 80 WP was observed. Decrease of yield of Mikon variety after application preemergence in autumn of Glean 57 DF and Stomp 330 EC, and after application in spring of Arelon Forte 61,5 WG was observed. The remaining herbicides were fully safe for tested varieties

Wheat flour tortillas were made from flour streams of three wheat cultivars: Jagger hard red winter wheat, 4AT-9900 hard white winter wheat, and Ernie soft red winter wheat. Wheat samples were milled on a Miag experimental mill. Twelve flour streams and one straight-grade flour were obtained. Tortillas were made from each flour stream and the straight-grade flour by the hot-press method. Tortilla stretchability and foldability were evaluated by a texture analyzer and six panelists, respectively. Flour protein and water absorption affected tortilla texture. The foldability evaluated by panelists was positively correlated with flour protein content, farinograph water absorption, and damaged starch (P < 0.05). The 2BK and 3BK streams of hard wheat produced tortillas with strong stretchability and good foldability. Middling streams of hard wheat yielded tortillas with lighter color and less stretchability. Under the conditions tested in this study, soft wheat flours were not good for producing flour tortillas.

Annual lespedezas [Kummerowia stipulacea (Maxim) Makino] have the potential to produce high quality forage during late summer when warm season forages are low in production and quality. A field study was conducted from 1992 through 1994 to determine DM, N, and digestible dry matter (DDM) production of three annual lespedeza cultivars (Korean, Kobe, and Marion). These cultivars were intercropped into two different continuous winter wheat (Triticum aestivum L.) production systems. Wheat was established in the fall under low tillage procedures in a 24-arce field, and grazed by steers from mid-November to mid-March at a stocking rate of 1 steer/acre. Before the wheat had reached the jointing stage, small plots were identified within the 24-acre wheat field. Inoculated lespedeza seeds were sown into the standing winter wheat in these plots, but grazing was continued on the plots and the field. At jointing, grazing was terminated on half of the plots (UNGRAZED), while the other half of the plots were grazed (GRAZED) until early May. Samples of lespedeza were collected at 18 to 20 d intervals beginning in late-June and ending in late-September, in time for the next wheat crop to be planted. All treatments were fixed in space and repeated on the same plots each year. Data were analyzed within year as a randomized complete block with cultivar as the main effect. In 1993 and 1994 Kobe produced DM, N, and DDM more (P < 0.05) under the UNGRAZED than the GRAZED management system. Management system had no effect on DM, N or DDM yield of Korean. When precipitation was above normal, Marion yielded more (P < 0.05) DM in the UNGRAZED plots than in the GRAZED plots, but Marion yield was inferior to that of Kobe and Korean under dry conditions. These results suggest that lespedeza can be intercropped in winter wheat to produce high quality forage during the summer. The availability of high quality forage, especially in late summer, can add sustainability to the livestock component of integrated livestock and winter wheat production systems in the southern Great Plains (SGP). Research QuestionA viable livestock enterprise in the southern Great Plains (SGP) requires a constant supply of high quality forage to reduce the cost of supplemental feed. Livestock systems in SGP are seasonally integrated to use winter wheat pasture and warm season perennial grasses. Livestock are used to grazing winter wheat in the fall and winter, but in the spring the producers must select one of two options: (i) continuing to graze the wheat at a higher stocking rate, or (ii) terminate grazing to produce a grain crop. In either option, the fields are fallowed for 90 to 120d during the summer. If tillage is used to keep the fields free of weeds during the summer, soil loss due to wind erosion is increased. At the same time that the producer is managing the fallow wheat fields, the livestock component of the enterprise needs high quality forage to offset the decline in forage quality of the perennial warm season grasses The objective of this study was to determine the feasibility of using annual les-pedeza intercropped into winter wheat to provide high quality forage in late summer when warm season perennial grasses are low in quality. Literature SummaryAnnual lespedezas are warm season herbaceous legumes that are most productive when cool season legumes or warm and cool season grasses are unproductive. These lespedezas are dependable reseeders, relatively tolerant to drought and pests, and can provide high quality nonbloating forage. Annual lespedezas are considered to be relatively free of diseases and will persist for years when allowed to reseed. Little information is available on the seasonal forage production capabilities and nutritive value of annual lespedezas under different continuous no-till winter wheat production systems in the SGP region. Study DescriptionA 3-yr field study was conducted from 1992 through 1994 to evaluate three annual lespedeza cultivars (Korean, Kobe, and Marion) on a Norge silt loam near El Reno, OK. Each spring, lespedeza seeds were inoculated and seeded with Brillion seeder into winter wheat that was being grazed by cattle. At wheat jointing, grazing was terminated on half of the plots (UNGRAZED), while grazing was continued on the other half of the plots (GRAZED). Samples were collected at 18 to 20 d intervals beginning in late June and ending in September, and analyzed for dry matter (DM), N, and in vitro dry matter digestibility (IVDMD) content. Yield of N and digestible DM was calculated by multiplying N and IVDMD concentrations by DM yield. Applied QuestionsAre DM yield and N produced by lespedezas intercropped into no-till winter wheat affected by grazing management of the wheat crop? The amount of DM and N accumulated by three different lespedeza cultivars (Korean, Kobe, and Marion) were affected by the variation in daily temperature and precipitation amounts and patterns. Grazing management of winter wheat altered the amount of residue cover, which in turn affected soil temperature and soil water evaporation; this resulted in a management × cultivar interaction. In years when soil moisture was limiting, late maturing cultivar (Kobe), and plots with wheat residue (UNGRAZED) produced more DM than plots of early maturity cultivars (Korean and Marion), and with little residue left on the soil surface (GRAZED). Lespedeza can be intercropped with winter wheat to produce high quality forage during late summer when the quantity and quality of warm season grasses are declining, but spring management of the wheat fields can affect the amount of DM produced.

Seasonal climate forecasting depends implicitly on climate mechanisms that behave predictably over season-to-season or longer time scales. One mechanism that shows evidence of such behavior is the El Niño-Southern Oscillation (ENSO). Using U.S. Climate Division data, USDA-NASS yield data, and the sea-surface temperature (SST) index of Wright (1989), the effects of both El Niño and La Niña Southern Oscillation phases on the central USA are evaluated, with a specific focus on comparing climate and agricultural yield effects during summer and winter. The climate analyses presented here reveal evidence of significant shifts in seasonal precipitation and temperature over parts of the central USA, dependent on the state of ENSO-associated SST anomalies. A significant tendency to cool and wet conditions over portions of the Missouri River drainage basin is found during El Niño July–August– September (JAS) periods. During JAS periods consistent with strong La Niña conditions a significant incidence of seasonal temperatures in the highest 25% of the historical record is found over Iowa, Illinois, and Indiana. El Niño conditions during northern winter are consistent with a higher-than-chance incidence of wet seasonal conditions over winter wheat (Triticum aestivum L.) growing regions of Texas, Oklahoma, and Kansas. Conversely, La Niña conditions show a significant tendency to below median precipitation and extreme dryness. A general tendency for winter wheat yields to be increased (decreased) is found in harvests after periods of warm (cold) winter SST, and a similar effect on corn (Zea mays L.) yield is found immediately after summer seasons marked by anomalously warm and cold SSTs in the equatorial Pacific. However, while significant tendencies for above or below normal yields are the rule in the winter wheat analyses, effects on corn yield—while clearly evident in some state's yield records—are less significant overall. This contrast in yield effect, combined with evidence of stronger northern winter climate impacts and the fact that the ENSO mechanism favors northern winters, lead us to propose that the value of ENSO forecasts of opportunity in long-term agricultural management may be greater for winter wheat than for corn. Research QuestionThe El Niño-Southern Oscillation (ENSO) mechanism is an important and potentially predictable source of variability in the Earth's climate system. However, its effects over the grain producing regions of the Great Plains and Midwest are not well resolved, particularly with regard to where agriculturally important climate effects occur and which growing seasons are most strongly affected. Important issues addressed here are the relative frequency and strength with which ENSO affects winter and summer climate over the central USA, and the relative degree to which those climate effects affect winter wheat and corn yields. Literature SummaryEarly research indicated that both the El Niño and La Niña phase of the ENSO mechanism affected precipitation during the winter and early spring over southern portions of the central USA. Subsequent work presented evidence of climate effects over the Corn Belt and the Northern Plains during summer. Most studies concentrating on ENSO-related yield effects have focused on summer crops such as corn, even though the strongest climate impacts over North America typically occur during the northern winter. Study DescriptionThe climate analysis method used here compares the distribution of seasonal climate values sampled during periods consistent with ENSO conditions against a null hypothesis that assumes random sampling. This approach first samples cumulative rainfall and mean temperature values of U.S. Climate Division Data during 3 mo seasonal periods marked by El Niño and La Niña sea-surface temperatures (SSTs) in the eastern equatorial Pacific. Next, the incidence of those sampled values above or below a season's historical median, and in the highest and lowest 25% of the historical record, is tested for deviation inconsistent with random sampling at an approximate 90% confidence level. After the identification of statistically significant and relevant seasonal climate effects, related effects on subsequent crop yield were evaluated through a similar statistical analysis of USDA-NASS per-acre corn and winter wheat yields. Applied QuestionsWhat significant climate effects were apparent? During El Niño July–August–September (JAS) periods, a significant incidence of relatively cool and wet growing conditions was found over the lower Missouri River drainage region. During JAS seasons consistent with strong La Niña conditions, a tendency toward seasonal temperatures in the uppermost 25% of historical values was found over the Corn Belt states of Iowa, Illinois, and Indiana. During El Niño winters (December–January–February) a significant tendency for precipitation above the median and in the highest 25% is indicated over important winter wheat growing regions of Texas, Oklahoma, Kansas, and Nebraska. Conversely, during La Niña November–December–January periods, a significant tendency for seasonal precipitation below the median and in the lowest 25% was found over portions of Texas, Oklahoma, Kansas, and Nebraska. How do yield effects on corn compare with yield effects on winter wheat? At a 90% confidence level or better, winter wheat yields in all five wheat producing states considered (Texas, Oklahoma, Kansas, Nebraska, and Colorado) showed a significant tendency to below normal values after November– December–January periods marked by cold La Niña SSTs. Conversely, a significant tendency to above normal yields was found after El Niño December–January–February periods in four of those five states. Thus a significant yield effect linking anomalously cold (warm) winter SSTs to subsequent decreases (increases) in wheat yield was found in four of the five wheat producing states. However, of the five corn producing states considered here (Illinois, Indiana, Iowa, Nebraska, and Minnesota), a comparable linear yield effect in corn harvests immediately after El Niño and La Niña summers was found only in Illinois and Indiana. Generally speaking, the effects of both ENSO phases appeared more consistent in winter wheat yields than in corn yields. What do these results imply for long-term agricultural management? The ability to forecast the state of SST, combined with evidence of significant SST-climate effects and plausible subsequent yield effects, implies the potential for forecasting those effects. The potential for adjusting management strategy in response to anticipated shifts in growing conditions is also implied. However, the fact that the ENSO mechanism is an intermittent feature of inter-annual climate will restrict such forecasts to occasional forecasts of opportunity. As a result, we make an analogy between the use of ENSO forecasts in long-term agricultural management and being given occasional access to loaded dice in an ongoing gambling situation; i.e., agriculture's year-to-year gamble on seasonal growing conditions. Noting the ENSO mechanism's preference for northern winters and the more pronounced effects on winter climate and winter wheat yield found here, we extend the analogy. That is, we suggest that producers of winter wheat may be offered such dice more frequently in the long term, and that they may be more heavily weighted towards certain climate and yield out comes. Stated more directly, we propose that the value of ENSO forecasts of opportunity in long-term agricultural management may be greater for winter wheat producers than for corn producers.

The accumulation of nitrogen in winter wheat plants during different stages of their growth and development has been studied. The trials carried out on the experimental field of the Latvia University of Agriculture in 1997 are described. Two winter wheat varieties - the mid-intensive "Sirvinta - 1" and the intensive variety "Otto" were investigated. The investigation results show that: 1) the highest nitrogen content in different parts of winter wheat plants is reached in the stooling stage; 2) in the flowering stage the movement of nitrogen to the reproductive parts of wheat plants is observed; 3) in all plant development stages there is a close positive correlation between the total nitrogen content in the above ground plant parts and the protein content in grain.