291. Assessment of vegetation response to drought in Nebraska using Terra-MODIS land surface temperature and normalized difference vegetation index.

• Authors:
  • Tadesse, T.
  • Narumalani, S.
  • Wardlow, B. D.
  • Swain, S.
  • Callahan, K.
• Source: GIScience & Remote Sensing
• Volume: 48
• Issue: 3
• Year: 2011
• Summary: Eight-day composite Terra-MODIS cumulative LST and NDVI timeseries data were used to analyze the responses of crop and grassland cover types to drought in Nebraska. Four hundred ninety 1 km pixels that included irrigated and non-irrigated corn and soybeans and three grassland cover types were selected across the state of Nebraska. Statistical analyses revealed that the majority of the land cover pixels experienced significantly higher daytime and nighttime LSTs and lower NDVI during the drought-year growing season ( p

292. Survey of moulds and mycotoxin contamination of cereals in South-Eastern Romania in 2008-2010.

• Authors:
  • Calin, L.
  • Taranu, I.
  • Tabuc, C.
• Source: Archiva Zootechnica
• Volume: 14
• Issue: 4
• Year: 2011
• Summary: Fungal mycoflora and mycotoxin contamination were determined in 86 samples (21 maize, 21 wheat, 11 barley, 4 oats, 1 rye, 12 soya, 6 sunflower, 4 colza, 3 rice, 3 triticale), coming from the south-eastern part of Romania during the 2008 to 2010 period. The most frequent fungal contaminants belonged to the Aspergillus and Fusarium genera, maize was the most contaminated cereal. The main toxinogenic species identified were A. flavus, A. fumigatus, F. graminearum, F. culmorum in all cereals Aflatoxin B1 (AFB1), ochratoxin A (OTA), deoxynivalenol (DON), zearalenone (ZEA) and fumonisins (FUMO), contents were analyzed by ELISA. More than 90% of the samples were found to be contaminated by at least one toxin. The most frequent mycotoxin was the deoxynivalenol (71.60%). Around 40% of samples were contaminated with AFB1 and FB. Ochratoxine A and zearalenone were found in 16% and 32% of samples respectively. These results demonstrated that cereals produced in Romania present a particular pattern of fungal mycoflora and mycotoxin contamination since DON, ZEA and FUMO as well as AFB1 and OTA were observed.

293. Study of the correlation between eight soybean cultivars in Xinjiang and their main production traits.

• Authors:
  • Liu, T.
  • Yang, X. K.
  • Zhang, H. B.
  • Zhan, Y.
  • Tian, H. Y.
• Source: Xinjiang Agricultural Sciences
• Volume: 48
• Issue: 11
• Year: 2011
• Summary: Objective: Xinjiang has a continental climate and irrigated oasis agriculture. Soybean sowing acreage has been expanded year by year, so its yield gradually increased. No doubt, the development of soybean production in Xinjiang is becoming more and more important. Soybean yield traits are dependant on plant height, stem section number, pod number per plant, grains per plant, grain weight and other forms. At the same time, yield is also a composite character, decided by plant height, stem section number, pod number per plant, grains per plant, kernel weight, and many other factors. This paper aims to study the correlation between the yield of the main soybean cultivars and their yield traits so as to provide a reference index for breeding or improving new varieties in Xinjiang. Method: Gray correlation analysis of eight cultivars planted in 2010 in Shihezi area, Northern Xinjiang was conducted in this paper. Conclusion: Soybean production yield traits associated with major degrees from high to low is shown as follows: kernel weight > plant grains > stem section number > number of pods per plant > plant height. The result has practical significance for setting the goals of breeding or improving soybean varieties.

294. Nitrogen use efficiency of irrigated corn for three cropping systems in Nebraska.

• Authors:
  • Dobermann, A. R.
  • Shapiro, C. A.
  • Tarkalson, D. D.
  • Wortmann, C. S.
  • Ferguson, R. B.
  • Hergert, G. W.
  • Walters, D.
• Source: Agronomy Journal
• Volume: 103
• Issue: 1
• Year: 2011
• Summary: Nitrogen use efficiency (NUE) is of economic and environmental importance. Components of NUE were evaluated at in 32 irrigated corn (Zea mays L.) trials conducted across Nebraska with different N rates and where the previous crop was either corn (CC), drybean ( Phaseolus vulgaris L.) (CD), or soybean [Glycine max (L.) Merr.] (CS). The mean grain yield with adequate nutrient availability was 14.7 Mg ha -1 When no N was applied, measured soil properties and irrigation water N accounted for <20% of the variation in plant nitrogen uptake (UN). Mean fertilizer N recovery in aboveground biomass was 74% at the lowest N rate compared with 40% at the highest N rate, a mean of 64% at the economically optimal nitrogen rate (EONR), and least with CD. Agronomic efficiency of fertilizer N averaged 29 kg grain kg(-1) N at EONR and was also least with CD. Partial factor productivity of N averaged 100 kg grain kg(-1) N at EONR, and was greater with CS compared with CC and CD. Aft er harvest, residual soil nitrate nitrogen (RSN) in the 0- to 1.2-m depth ranged from 21 to 121 kg ha(-1) and increased with N rate. Mean RSN was 88, 59, and 59 kg ha(-1) for CD, CC, and CS, respectively. High corn yields can be achieved with high NUE and low RSN by management to maximize profitability in consideration of yield potential, and by applying N at the right amount and time.

295. In-season prediction of corn yield using plant height under major production systems.

• Authors:
  • Tyler, D. D.
  • Jaja, N.
  • McClure, M. A.
  • Yin, X. H.
  • Hayes, R. M.
• Source: Agronomy Journal
• Volume: 103
• Issue: 3
• Year: 2011
• Summary: The relationship between corn ( Zea mays L.) yield and plant height has been poorly documented in major corn production systems. This study was conducted to assess the relationship of corn yield with plant height under four major corn production systems at Milan, TN from 2008 through 2010. Six N treatments at rates of 0, 62, 123, 185, 247, and 308 kg N ha -1 with four replications were evaluated in a randomized complete block design in the following corn production systems: nonirrigated corn after corn, nonirrigated corn after soybean [ Glycine max (L.) Merr.], nonirrigated corn after cotton [ Gossypium hirsutum (L.)], and irrigated corn after soybean. The regression of corn yield with plant height was significant and positive at 6-leaf growth stage (V6), 10-leaf growth stage (V10), and 12-leaf growth stage (V12), and mostly became stronger as plant growth progressed from V6 to V10 and to V12 under an exponential model in the four corn production systems for all 3 yr. In general, corn yield was strongly related with plant height measurements made at V10 and V12. Factors affecting the responses of plant height measured at V6, V10, and V12 or/and yield to the N treatments may have contributed to the variations of determination coeffient ( R2) values across years. In conclusion, corn yield may be predicted with plant height measurements collected during V10 to V12. This prediction provides a physiological basis for the utilization of high resolution plant height measurements to guide variable-rate N applications within the field on corn at around V10 and to more accurately estimate yield for earlier grain marketing purposes.

296. Agricultural water productivity assessment for the Yellow River Basin.

• Authors:
  • You, L. Z.
  • Zhao, J. S.
  • Ringler, C.
  • Yang, Y. C. E.
  • Cai, X. M.
• Source: Agricultural Water Management
• Volume: 98
• Issue: 8
• Year: 2011
• Summary: Agricultural water productivity (WP) has been recognized as an important indicator of agricultural water management. This study assesses the WP for irrigated (WPI) and rainfed (WPR) crops in the Yellow River Basin (YRB) in China. WPI and WPR are calculated for major crops (corn, wheat, rice, and soybean) using experimental, statistical and empirically estimated data. The spatial variability of WPI and WRR is analyzed with regard to water and energy factors. Results show that although irrigated corn and soybean yields are significantly higher than rainfed yields in different regions of the YRB, WPI is slightly lower than WPR for these two crops. This can be explained by the seasonal coincidence of precipitation and solar energy patterns in the YRB. However, as expected, irrigation stabilizes crop production per unit of water consumption over space. WPI and WPR vary spatially from upstream to downstream in the YRB as a result of varying climate and water supply conditions. The water factor has stronger effects on both crop yield and WP than the energy factor in the upper and middle basin, whereas energy matters more in the lower basin. Moreover, WP in terms of crop yield is compared to that in terms of agricultural GDP and the results are not consistent. This paper contributes to the WP studies by a basin context, a comparison between WPI and WPR, a comparison of WP in terms of crop yield and economic value, and insights on the water and energy factors on WP. Moreover, policy implications based on the WP analysis are provided.

297. Weed Incidence in Grain Production Systems

• Authors:
  • Negrisoli, E.
  • Crusciol, C. A. C.
  • Castro, G. S. A.
  • Perim, L.
• Source: Planta Daninha
• Volume: 29
• Year: 2011
• Summary: Tillage and other agricultural production systems can contribute to weed suppression. Thus, the objective of this study was to evaluate weed control using different grain production systems. The treatments were: I. "Harvest-fallow" System-soybean/fallow/corn/fallow/rice/fallow/soybean; II. "Harvest-green manure" System-soybean/millet/maize/pigeon pea/rice/Crotalaria/soybean; III. "Harvest-out of season" System-soy/white oats/corn/dry bean/rice/castor oil/soybean; and IV "Harvest-fodder" System-brachiaria + soy/corn + brachiaria/brachiaria + rice/soybeans. A weed survey was carried out in November 2009, after three growing seasons. A 0.3 x 0.3 m frame was randomly launched four times within each plot. The plants were identified, and the total number of weeds, dry weight, and control percentage of the species were determined according to the production system. The phytosociological analysis of the weed community was also conducted. The systems Harvest-green manure; Harvest-out of season and Harvest-fodder presented a good weed control when compared to the Harvest-fallow system. Therefore, the presence of some type of soil cover is important to maintain favorable soil characteristics and good weed control.

298. Corn-soybean intercropping: temporal and spatial variation of soil properties.

• Authors:
  • Giuffre, L.
  • Giardina, E. B.
  • Ciarlo, E. A.
  • Garcia Torres, T. P.
• Source: REVISTA FACULTAD DE AGRONOMÍA Universidad de Buenos Aires
• Volume: 31
• Issue: 1/2
• Year: 2011
• Summary: The dynamics of nutrient availability and other soil properties can be strongly altered by agricultural practices like intercropping. A test was made on an agricultural soil with the following treatments: (i) sole cropped soybean, (II) sole cropped maize and (III) intercropped corn-soybean in a 1:2 ratio. Surface soil samplings were made in two moments: the first one (F1) was made with corn at V5 and soybean just emerged; the second one (F2) with corn crop at R1 and soybean crop at V7-R1, both at two distances of the furrows: 5 and 19 cm. Oxidizable C contents were always maximum at the treatments including corn cropping. At both dates, extractable P was maximum at sole corn and minimum at sole soybean crop, which can be attributed to a strong uptake by the leguminous plant. In the first measurement date, at 5 cm of the corresponding furrow, nitrate availability was significantly greater at the soybean treatments with respect to treatments including corn, whereas in the second date, nitrate availability was minimum at sole soybean, which seems to be due to differences in crops development. Finally, the practice of intercropping, within the frame of this test, did not prove to be a viable alternative to limit the existence of high nitrate levels.

299. Simulating the effects of climate and agricultural management practices on global crop yield.

• Authors:
  • Barford, C. C.
  • Sacks, W. J.
  • Deryng, D.
  • Ramankutty, N.
• Source: Global Biogeochemical Cycles
• Volume: 25
• Issue: 2
• Year: 2011
• Summary: Climate change is expected to significantly impact global food production, and it is important to understand the potential geographic distribution of yield losses and the means to alleviate them. This study presents a new global crop model, PEGASUS 1.0 (Predicting Ecosystem Goods And Services Using Scenarios) that integrates, in addition to climate, the effect of planting dates and cultivar choices, irrigation, and fertilizer application on crop yield for maize, soybean, and spring wheat. PEGASUS combines carbon dynamics for crops with a surface energy and soil water balance model. It also benefits from the recent development of a suite of global data sets and analyses that serve as model inputs or as calibration data. These include data on crop planting and harvesting dates, crop-specific irrigated areas, a global analysis of yield gaps, and harvested area and yield of major crops. Model results for present-day climate and farm management compare reasonably well with global data. Simulated planting and harvesting dates are within the range of crop calendar observations in more than 75% of the total crop-harvested areas. Correlation of simulated and observed crop yields indicates a weighted coefficient of determination, with the weighting based on crop-harvested area, of 0.81 for maize, 0.66 for soybean, and 0.45 for spring wheat. We found that changes in temperature and precipitation as predicted by global climate models for the 2050s lead to a global yield reduction if planting and harvesting dates remain unchanged. However, adapting planting dates and cultivar choices increases yield in temperate regions and avoids 7-18% of global losses.

300. Nitrogen response and economics for irrigated corn in Nebraska.

• Authors:
  • Tarkalson, D. D.
  • Shapiro, C. A.
  • Hergert, G. W.
  • Ferguson, R. B.
  • Wortmann, C. S.
  • Dobermann, A.
  • Walters, D. T.
• Source: Agronomy Journal
• Volume: 103
• Issue: 1
• Year: 2011
• Summary: Nitrogen management recommendations may change as yield levels and efficiency of crop production increase. The mean yield with nutrients applied in 32 irrigated corn ( Zea mays L.) trials conducted across Nebraska from 2002 to 2004 to evaluate crop response to split-applied N was 14.8 Mg ha -1 The mean economically optimal nitrogen rates (EONR) for irrigated corn varied with the fertilizer N/grain price ratio. At a fertilizer N/corn price ratio of 7 the EONR was 171, 122, and 93 kg ha -1, respectively, for cropping systems with corn following corn (CC), soybean [ Glycine max (L.) Merr.] (CS), and drybean ( Phaseolus vulgaris L.) (CD). At this price ratio the present University of Nebraska (UNL) recommendation procedure gave mean N recommendations that were 17.2 and 68.1 kg ha -1 higher than the mean EONR determined in this study for CC and CD, respectively, but essentially equal to mean EONR for CS. The UNL algorithm, adjusted for mean cropping system EONR gave more accurate prediction of site-year EONR than alternative N rate predictions for CC and CD with returns to applied nitrogen (RTN) of -$22 and -$13 ha -1 compared with measured site-year EONR. Prediction of site-year EONR using mean EONR adjusted for soil organic matter was more accurate for CS than other methods with an RTN of -$6 ha -1 compared with measured site-year EONR. Further research is needed to extend the results to: lower yield situations, alternatives to split application of N, and adjustment of EONR to protect against inadequate N in atypical seasons or for environmental protection.