• 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.
  • Authors:
    • Ouyang, W.
    • Wang, Y. H.
    • Wang, X.
    • Hao, F. H.
    • Zhang, X.
  • Source: Transactions of the Chinese Society of Agricultural Engineering
  • Volume: 27
  • Issue: 6
  • Year: 2011
  • Summary: To assess the phosphorus loss under different crops cultivations in farmland, soil samplings were taken in four typical crop types' fields in five layers of 0-100 cm. Based on the isothermal methane-adsorbing experiments, SPSS software was applied to analyze the results statistically. The phosphorus loss potential was evaluated and the influence factors were discussed in this paper. The results revealed that the sorption characteristics of all the soil samples in the study area could be described by Langmiur and Freundich equations, and the Langmiur equation fit better. The soil in wheat field showed better sorption of phosphorus than that of other crops. The soil samples of intercropping field demonstrated poor sorption capacity. The phosphorus sorption of the top soil in the different crop fields showed few variations. Compared with the phosphorus sorption of the deeper layers, the top soil was prone to lose along with farmland drainage except in the intercropping field, where the phosphorus loss with seepage vertically into groundwater was the preferential way. Phosphorus sorption index (PSI) was another effective parameter to assess the phosphorus loss potential except for the theoretically maximum sorption capacity Qm and the equilibrium phosphorus concentration at zero sorption (EPC 0). The conclusions of this paper can provide scientific references for appropriate scheduling on efficient fertilization, irrigation, and non-point source pollution control.
  • Authors:
    • Gomez-Macpherson, H.
    • Mateos, L.
    • Boulal, H.
  • Source: Irrigation Science
  • Volume: 29
  • Issue: 5
  • Year: 2011
  • Summary: Zero tillage and controlled traffic have been proposed as means for more productive and sustainable irrigated farming. Both practices affect soil infiltration characteristics and, therefore, should have effects on sprinkler irrigation performance. This study compared water infiltration and runoff in three sprinkler irrigation tests performed on an alluvial loam soil at different times during a maize (Zea mays L.)-cotton (Gossypium hirstium L.) rotation under two soil managements: permanent beds with crop residue retention (PB: planting beds maintained unaltered from year to year) and conventional beds with residues incorporated with tillage (CB: disc and chisel ploughing followed by rotavator pass and bed forming every year). Traffic was controlled and two types of furrows were distinguished in both tillage systems: with (+T) and without (-T) wheel traffic. The irrigation tests were performed on maize at full cover, on bare soil just before cotton sowing and on cotton with 50% ground cover. Infiltration and runoff were affected notably by both traffic and soil management. The soil under PB infiltrated more water than under CB, and -T furrows more than +T furrows. Considering the combined treatments, -T furrows in the CB system infiltrated more water than +T furrows in the PB system. A sprinkler irrigation model for simulating water application and soil infiltration and runoff was formulated. The model was used to analyse irrigation performance under infiltration characteristic of the CB and PB systems in trafficked and non-trafficked furrows. Five irrigation performance indicators were used to assess the various combinations of tillage and traffic: Wilkox-Swailes coefficient of uniformity; application efficiency; deep percolation ratio; tail water ratio; and adequacy. The model was used to develop operation diagrams and provided guidelines for making irrigation decisions in the new controlled traffic/permanent bed system and in a standard conventional system.
  • Authors:
    • Almeida, N. A.
    • Oliveira, I. R. de
    • Carvalho, L. M. de
    • Andrade, K. R.
  • Source: Acta Horticulturae
  • Issue: 925
  • Year: 2011
  • Summary: Fennel ( Foeniculum vulgare Miller), Apiaceae, a spice and medicinal plant from the Mediterranean region, is grown by family farmers without irrigation and under high temperature conditions of the Brazilian northeast. In this study, a field experiment was done in the semi-arid region of Sergipe state, Brazil, to evaluate the performance of fennel-bean intercrop under organic management, using a completely randomized block design with six replications and four treatments (fennel monocrop and fennel intercropped (additive model)) with two cultivars of beans ( Phaseolus vulgaris) and one cultivar of cowpea ( Vigna unguiculata). Fennel plants were obtained from seeds and transplanted into the field at the beginning of the rainy season in June, while seeds of the beans and cowpea were being sown. Umbels of the fennel were harvested in January, 210 days after transplanting the fennel into the field. The fresh and dry mass of umbels, absolute and relative yield, land equivalent ratio (LER) and essential oil content were improved under the intercrop with cowpea and one cultivar of bean. No significant differences were detected on height and canopy areas among treatments, but any decrease in yield of fennel plants associated with intercrops with cowpea or bean were small. The intercrops studies confirmed the viability of intercropping fennel with cowpeas and beans.
  • Authors:
    • Mehla, R. S.
    • Punia, M.
    • Ladha, J. K.
    • Khurana, M. L.
    • Chandna, P.
    • Gupta, R.
  • Source: Environmental Monitoring & Assessment
  • Volume: 178
  • Issue: 1-4
  • Year: 2011
  • Summary: Increased use of nitrogenous fertilizers in the intensively cultivated rice (Oryza sativa)-wheat (Triticum aestivum) cropping system (covers a 13.5-ha m area in South Asia) has led to the concentration of nitrates (NO(3)-N) in the groundwater (GW) in Haryana State of India. Six districts from the freshwater zone were selected to identify factors affecting NO(3)-N enrichment in GW. Water and soil samples were collected from 1,580 locations and analyzed for their chemical properties. About 3% (26,796, and 10,588 ha) of the area was estimated to be under moderately high (7.5-10 mg l (-aEuro parts per thousand 1)) and high (> 10 mg l (-aEuro parts per thousand 1)) risk categories, respectively. The results revealed that NO(3)-N was 10-50% higher during the pre-monsoon season than in the monsoon season. Nitrate-N decreased with the increase in aquifer depth (r (2) = 0.99). Spatial and proximity analyses using ArcGIS (9.2) revealed that (1) clay material in surface and sub-surface texture restricts N leaching, (2) piedmont and rolling plains act as an N sink, and (3) perennial rivers bring a dilution effect whereas seasonal rivers provide favorable conditions for NO(3) (-) enrichment. The study concludes that chemical N fertilizers applied in agro-ecosystems are not the sole factor determining the NO(3) in groundwater; rather, it is an integrated process governed by several other factors including physical and chemical properties of soils, proximity and type of river, and geomorphologic and geographical aspects. Therefore, future studies should adopt larger area (at least watershed scale) to understand the mechanistic pathways of NO(3) enrichment in groundwater and interactive role of the natural drainage system and surrounding physical features. In addition, the study also presents a conceptual framework to describe the process of nitrate formation and leaching in piedmont plains and its transportation to the mid-plain zone.
  • Authors:
    • Klein, D.
    • Dech, S.
    • Colditz, R. R.
    • Conrad, C.
    • Vlek, P. L. G.
  • Source: International Journal of Remote Sensing
  • Volume: 32
  • Issue: 23
  • Year: 2011
  • Summary: Crop cover and crop rotation mapping is an important and still evolving field in remote sensing science for which robust and highly automated processing chains are required. This study presents an improved mapping procedure for crop rotations of irrigated areas in Central Asia by using classification and regression trees (CARTs) applied to transformations of 250 m Moderate Resolution Imaging Spectroradiometer (MODIS) Normalized Difference Vegetation Index (NDVI) time series. The time series were divided into several temporal segments, from which metrics were derived as input features for classification. This temporal aggregation was applied to suppress within-class temporal variability. Various lengths of temporal segments were tested for their potential to increase classification accuracy. In addition, tests of enhancing the classification accuracy were done by combining different classification results using the majority rule for voting. These different processing strategies were applied to four annual time series (2004-2007) of the Khorezm region, where 270 000 ha of irrigated land is dominated by rotations of cotton, wheat and rice. Improved classification results were obtained for CARTs applied to metrics derived from a mixture of different segment lengths. The sole use of either long or short temporal segments was inferior. CART prioritized segments representing active phases of the phenological development. The best result, the optimized segment-based approach, achieved an overall accuracy between 83 and 85% for classifications between 2004 and 2007; in particular, the small range demonstrated the robustness regarding inter-annual variations. These accuracies exceeded those of the original time series without temporal segmentation by 6-7%. With some adjustments to other crops and field heterogeneity influencing the usefulness of a respective sensor, the approach can be applied to other irrigation systems in Central Asia.
  • Authors:
    • Sanavy, S. A. M. M.
    • Dolatabadian, A.
    • Ghanati, F.
  • Source: Notulae Scientia Biologicae
  • Volume: 3
  • Issue: 1
  • Year: 2011
  • Summary: This research was conducted in order to evaluation the salinity stress effect on growth parameters and stem anatomical changes of soybean grown under controlled conditions. Soybean seeds were surface sterilized and then sown into plastic pots filled up with perlite and vermiculite. Seeds were irrigated with Broughton and Dilworth solution daily. At full folded cotyledons stage (5 day after sowing), salinity stress was induced by adding NaCl into nutrition solution with final concentration of 0, 25, 50 and 100 mM. Thirty days after sowing plants were harvested and growth parameters and anatomical changes were evaluated. The results showed that, salinity stress was significantly decreased shoot and root weight either fresh weight or dry weight, in addition, total plant weight, plant height and leaf number were decreased due to salinity stress. Interestingly, leaf area was not affected by salinity stress. Stem microscopic study demonstrated that, salinity stress significantly increased cutin mass and trichome density on epidermal cells. On the other hand, cortex thickness was decreased because of salinity stress while xylem thickness had upward increase when soybean plants were grown under salinity stress especially high level of salinity. Additionally, there were changed in xylem formation and arrangement in stressed plants.
  • Authors:
    • Finetto, G. A.
  • Source: Acta Horticulturae
  • Issue: 890
  • Year: 2011
  • Summary: Afghanistan can be considered the country of the pomegranate fruit because of the excellent quality of the cultivars that thrive there. Afghanistan is a land for 48 leading world cultivars of pomegranate commonly growing in Kandahar, Kapisa, Samangan, Farha, Nenroz and Balkh Provinces. Kandahar Province has historically, widely been known as main production area for its high quality and productivity. Other pomegranate orchards are located along the Arghandab River. Pomegranate ranks 5th after grapes, almond, apricot and apple. The area has decreased from 5667 ha (1996) to 2500 ha (2003). The average yields are in the range of about 8600 kg/ha in Dand district to more than 19000 kg/ha in Arghandab district. Although one estimate says the total production is around 24,000 Mt, a rational estimation is around 15-20,000 Mt, due to the poor production in some areas. Production in the Kandahar Province is approximately 10,000 metric tons; and the main cultivar is 'Kandahari'. Smaller volumes are produced elsewhere in Afghanistan. Elevation is the main restriction in production, with 'Bedana' produced in Nangarhar at or above 1000 m elevation. 'Kandahari' is produced at elevations from 550 m to below 1000 m. Up to now no collection of local cultivars has been carried out by the fruit tree projects funded by international organisations (EC, World Bank, FAO, USAID, DFID, ICARDA, etc.). To meet the high demand of the world market, Afghanistan must increase production levels and improve productivity through better husbandry of pomegranate orchards. In Afghanistan few are commercial orchards, commonly the farmers grow this fruit species in small plots with intercropping, due to very exiguous dimensions of farms (average 0.8 ha per household), dire needs of staple food for their families and an instable political situation. In spite of the good local cultivars few cultural practices such as irrigation, fertilisation, pruning, etc. are applied often in an unsteady way. Due to the health benefits of the fruit (anti-oxidant) several traders in Afghanistan have started to receive orders for pomegranate from outside their traditional markets in the Sub-Continent. So, locally the market for pomegranate does not compare with other more common fruits because the demand is growing rapidly. Pomegranate commercialisation has a typical supply chain that involves the following major players: Grower, Pre-harvest Contractor, Pakistani Importer/Financier, Packaging Company. From harvest to market, wooden baskets (typically 3 sizes, but without uniform size/weight), made of flexible pomegranate tree branches (1st or 2nd year shoots) are used. For export mostly wooden crates are used. Pomegranate is an ideal fresh fruit for Afghanistan to export as they come in a tough outer rind and have good storage properties. So, pomegranate should be considered as one of the most promising crops for support but refrigeration, postharvest handling and promotion should all be applied to this crop.
  • Authors:
    • Lawn, . J.
    • Gaynor, L. G.
    • James, A. T.
  • Source: Crop and Pasture Science
  • Volume: 62
  • Issue: 12
  • Year: 2011
  • Summary: Serial sowing date studies were used to examine the response of a diverse range of soybean genotypes to sowing date in the Murrumbidgee Irrigation Area (MIA). The aim was to explore the scope to improve the flexibility for rotating irrigated summer soybean crops with winter cereals by broadening the range of potential sowing dates. Serial sowings of diverse genotypes were made in small plots at intervals of ~7 days (2006-07) or 10 days (2007-08) from late November to late January (2006-07) or mid-February (2007-08) and the dates of flowering and maturity recorded. Simple linear models relating rate of development towards flowering to photo-thermal variables indicated that large differences in time to flowering between genotypes, sowing dates, and years could be explained in terms of differences in genotype sensitivity to mean photoperiod and/or mean daily temperature between sowing and flowering. In general, warmer temperatures hastened and longer days delayed flowering, consistent with quantitative short-day photoperiodic response. The earliest flowering genotypes were insensitive to the prevailing photoperiods, and their smaller variations in time to flower over sowing dates and years were related to temperature. Conversely, later flowering genotypes were progressively more sensitive to photoperiod, with flowering occurring later and being more responsive to sowing date. In both seasons, late maturing genotype * sowing date combinations suffered cold temperature damage and frosting. For those genotype * sowing date combinations that were physiologically mature before the first frost, crop duration was a linear function ( r2=0.86**) of time to flowering. In 2007-08, measurements were also made at maturity of total standing dry matter (TDM), seed yield, and seed size. For those genotype * sowing date combinations that matured before the first frost, TDM was largely a linear function ( r2=0.83**) of crop duration, while seed yield was strongly related ( r2=0.86**) to TDM. Exposure to cold temperatures before physiological maturity reduced seed size and harvest index. Using the generalised relations developed in these studies, it was concluded that commercial yields may be possible for irrigated soybean crops in the MIA sown in December or possibly later. These options are evaluated in greater detail in the companion paper, using large-scale agronomic trials of a subset of adapted genotypes.
  • Authors:
    • Burr, C.
    • Thorburn, J.
    • Irmak, S.
    • Yang, H. S.
    • Grassini, P.
    • Cassman, K. G.
  • Source: Field Crops Research
  • Volume: 120
  • Issue: 1
  • Year: 2011
  • Summary: Appropriate benchmarks for water productivity (WP), defined here as the amount of grain yield produced per unit of water supply, are needed to help identify and diagnose inefficiencies in crop production and water management in irrigated systems. Such analysis is lacking for maize in the Western U.S. Corn Belt where irrigated production represents 58% of total maize output. The objective of this paper was to quantify WP and identify opportunities to increase it in irrigated maize systems of central Nebraska. In the present study, a benchmark for maize WP was (i) developed from relationships between simulated yield and seasonal water supply (stored soil water and sowing-to-maturity rainfall plus irrigation) documented in a previous study; (ii) validated against actual data from crops grown with good management over a wide range of environments and water supply regimes ( n=123); and (iii) used to evaluate WP of farmer's fields in central Nebraska using a 3-y database (2005-2007) that included field-specific values for yield and applied irrigation ( n=777). The database was also used to quantify applied irrigation, irrigation water-use efficiency (IWUE; amount of yield produced per unit of applied irrigation), and the impact of agronomic practices on both parameters. Opportunities to improve irrigation management were evaluated using a maize simulation model in combination with actual weather records and detailed data on soil properties and crop management collected from a subset of fields ( n=123). The linear function derived from the relationship between simulated grain yield and seasonal water supply, namely the mean WP function (slope=19.3 kg ha -1 mm -1; x-intercept=100 mm), proved to be a robust benchmark for maize WP when compared with actual yield and water supply data. Average farmer's WP in central Nebraska was ~73% of the WP derived from the slope of the mean WP function. A substantial number of fields (55% of total) had water supply in excess of that required to achieve yield potential (900 mm). Pivot irrigation (instead of surface irrigation) and conservation tillage in fields under soybean-maize rotation had the greatest IWUE and yield. Applied irrigation was 41 and 20% less under pivot and conservation tillage than under surface irrigation and conventional tillage, respectively. Simulation analysis showed that up to 32% of the annual water volume allocated to irrigated maize in the region could be saved with little yield penalty, by switching current surface systems to pivot, improving irrigation schedules to be more synchronous with crop water requirements and, as a fine-tune option, adopting limited irrigation.