• Authors:
    • Xu, Z.
    • Cao, Z.
    • Chen, Y.
    • Liang, X.
    • Li, H.
    • Li, S.
  • Source: Journal of Soils and Sediments
  • Volume: 9
  • Issue: 5
  • Year: 2009
  • Summary: Background, aim, and scope - A large area of water eutrophication in the Tai Lake region of China was associated with nitrogen (N) and phosphorus (P) pollution, mainly due to the discharge of untreated rural wastewater (RW) into the surface water (SW) near villages of this region. A field experiment was conducted, using irrigation of RW plus urea fertilization under equal nitrogen (N) rate, namely, black water (BW), domestic wastewater (DW), gray water (GW), SW, and SW without any N application as a control (CK), to elucidate N removal by the paddy wetland system during the rice growing season of 2007. Materials and methods - SW, GW, DW, and BW were collected from the village of Liangzhu in subtropical China. Water samples were stored in darkness at 4°C in an icebox prior to analysis. Total nitrogen (TN) was analyzed by the spectrophotometric method with a continuous-flow automated analyzer. For the soil analyses, pH was measured using a pH meter with soil/distilled water=1:5; cation exchange capacity was determined with an unbuffered salt extraction method. Redox potential (Eh) was obtained using a pH meter with a platinum electrode, whereas organic carbon (C) was determined using the Walkley and Black method. TN was calculated by acid-alkali neutralization, after the soil samples were digested with concentrated sulfuric acid (H 2SO 4), distilled and then absorbed by diluted boric acid (H 3BO 3), and available N was determined by alkaline-proliferation law, after the samples were hydrolyzed, reduced, and absorbed by H 3BO 3. Available P was determined with the colorimetric method at the wave length of 660 nm, after the samples were extracted with NaHCO 3, and available K was extracted by unbuffered NH 4Cl and then determined by the atomic absorption spectrophotometer. The rice plant samples were digested with H 2SO 4-H 2O 2, and N contents were analyzed by the atomic absorption spectrophotometry. Results - Yield for the CK was significantly less ( P≤0.05) than those of SW, GW, DW, and BW, with the yield of BW significantly greater ( P≤0.05) than all the other treatments. The TN concentration of the floodwater in the paddy wetland system decreased rapidly after transplanting, rose significantly ( P≤0.05) after two N topdressings, and then decreased gradually as the following sequences: SW > GW > DW > BW > CK, but tended to be stable until 15 October. Meanwhile, TN removal rates from the wastewater were significantly higher ( P≤0.05) than those from the urea fertilizer. Total N load (TNL) increased significantly after two topdressings and reached the maximum value just after the first topdressing on 22 July: SW, 21.0 kg ha -1; GW, 19.1 kg ha -1; BW, 15.3 kg ha -1; DW, 14.3 kg ha -1; and CK, 0.57 kg ha -1. Subsequently, TNL declined gradually and reached stability on 15 October. Just after the rice seedlings were transplanted, the soil released a large amount of inorganic N (26.3%-40.4%); however, after the topdressing, the soil adsorbed a lot of N and TNL originating from the RW, which had decreased, ranging from 34.5% to 47.8%. Discussion - A reasonable N rate would be necessary for normal rice production in the Tai Lake region, which is different from those studies of other systems. Irrigation with RW for the paddy field could not only reduce the amount of commercial N fertilizer usage and irrigation water but also increase rice grain yield. Meanwhile, N use efficiency was improved by the combination of both N fertilizer and RW. The more N fertilizer was used, the higher the TN concentration in the flooded water would be, and the more potential risk of N to the surface water body. However, the N in RW could be removed more easily than that of the fertilizer by the paddy wetland system, which may be related to the existing form and concentration of N in the RW and urea fertilizer. The TNL in the floodwater had a positive correlation with the urea application rate, implying that appreciable amounts of N input might be lost, either by a heavy rainfall event or floodwater drainage using improper water management methods closely subsequent to the urea application. This revealed that using GW, DW, or BW instead of SW as irrigation water could decrease the loss of N applied and reduce the environmental pollution risk for the surface water. Conclusions - Supplemental N was necessary in this area for normal rice production, and the rice grain yield of CK (without any N fertilizer applied) was significantly lower than the other treatments; however, the yield of SW (with N fertilizer applied) was not significantly different from those of GW and DW. However, irrigation with RW in the paddy rice field could reduce costs of fertilizer and irrigation water. In addition, using BW would significantly increase rice yield revenues. The paddy wetland system also removed large quantities of N due to the irrigation with RW and applied N fertilizer, with the TN removal rates for RW significantly higher than that for the N fertilizer. Thus, application of RW instead of N fertilizer alone could greatly decrease the discharge of N into water bodies; thus, paddy wetland system can be considered as a new method for the RW treatment, especially in the Tai Lake region of China. Recommendations and perspectives - Based on this study, it would be strongly recommended to use RW irrigation after it had been disinfected for reducing part of commercial N fertilizer rate and saving some irrigation water in rice production with the paddy wetland system as a cost-effective way to remove the N from the RW and mitigate the non-point pollution. Future work should pay attention to the largest N-removal capacity of the paddy wetland system per unit and the effect on the rice grain quality irrigated with the RW.
  • Authors:
    • Elliott, N.
    • Michels, J.
    • Ansley, J.
    • Mirik, M.
  • Source: Southwestern Entomologist
  • Volume: 34
  • Issue: 2
  • Year: 2009
  • Summary: The Russian wheat aphid, Diuraphis noxia (Mordvilko), is a severe pest of wheat, Triticum aestivum L.; barley, Hordeum vulgare L.; other small grains; and grasses. Although the Russian wheat aphid is a significant pest of small grains, its feeding effects on grain yield and vegetative biomass in large-scale wheat fields have not been well documented. Data were collected for 3 years in dryland and irrigated wheat fields in Texas and Oklahoma. The insect reduced grain yield 50.2 to 82.9% and biomass by 55.4 to 76.5%. These results suggested that winter wheat suffers significant economic loss from Russian wheat aphid.
  • Authors:
    • Sharaiha, R.
    • Molla, A.
  • Source: Lucrari Stiintifice, Universitatea de Stiinte Agricole Si Medicina Veterinara "Ion Ionescu de la Brad" Iasi, Seria Agronomie
  • Volume: 52
  • Issue: 1
  • Year: 2009
  • Summary: Mixed intercropping of barley and wheat has been reported as the practice of smallholder farmers in some dryland areas of Ethiopia. However, this cropping system has not yet received the attention of research. Therefore, this study was conducted to determine the level of competition and yield advantage in barley and wheat mixed intercropping under different stress levels of moisture deficit. One pot and one field experiments were conducted to address these objectives. In the pot experiment, three irrigation water levels (75-80, 50-55, and 25-30% depletion of soil available water), five intercropping ratios (%) of barley to wheat in a replacement series (100/0, 75/25, 50/50, 25/75, and 0/100), and four planting densities (4, 8, 12 and 16 plants/pot) were studied in a split-split plot design and had three sets so as to harvest at tillering, heading and maturity stages. In the field, the five intercropping ratios and the four water levels supplied by sprinkler irrigation system were studied in a split-plot design. Intra- and inter-specific competition decreased with decreasing stress levels of moisture deficit; but increased with increasing planting densities in all harvesting stages in the pot experiment. However, both competition types were higher at tillering stage but progressively decreased in later harvesting stages. Intraspecific competition was more important for barley at early stages and for wheat at later stages of the growing period. Both pot and field experiments proved that barley was less competitive than wheat towards the reproductive stage. Yield advantage of mixed intercropping of barley and wheat increased with increasing stress levels of moisture deficit under study. Yield advantage and productivity tended to be dominated by the higher yielding crop species in the mixture. This result suggests mixed intercropping of barley and wheat is not a priority in areas where moisture is not limiting in amount and distribution. It is advisable to use 50% barley+50% wheat ratio since it is difficult to predict which crop performs better than the other in such unpredictable rainfall conditions of the drylands.
  • Authors:
    • Nowacki, W.
  • Source: Journal of Research and Applications in Agricultural Engineering
  • Volume: 54
  • Issue: 4
  • Year: 2009
  • Summary: In the paper, an influence of potato irrigation on higher level of total yield and changing share of market yield in total yield were evaluated. Profitability of using of drip irrigation was calculated taking into account the expenses and value of yield. Is was shown that in case of drought during the vegetation period yield the increase of potato yield due to irrigation in ecological system may achieve up to 25%. Potato quality is improved which is expressed by increased market yield. Relative high cost of drip irrigation are fully refund by increasing value of potato market yield. It is also possible to use the irrigation for increasing biomass production which comes from intercrop production used for ploughing.
  • Authors:
    • Gajbhiye, K. S.
    • Ray, S. K.
    • Prasad, J.
    • Singh, S. R.
  • Source: Agropedology
  • Volume: 19
  • Issue: 2
  • Year: 2009
  • Summary: Detailed soil survey of Selsura KVK research farm of Dr. P.D.K.V., Akola in Wardha district, Maharashtra was carried out using 1:6000 scale cadastral map. There were nine soil series and thirteen mapping units. The soils were very dark gray to very dark grayish brown in hue 10YR, calcareous and clayey but differed in depth and are classified under Entisols, Inceptisols and Vertisols. In general, pH (8.0-9.2) increased with depth whereas reverse trend was observed for organic carbon. Soils of Selsura-1 are prone to sodicity problems. DTPA-Zn and Fe were deficient in these soils but DPTA-Mn and Cu were optimum. The mapping units were grouped under II to IV land capability classes and 2 to 4 land irrigability classes. Except soils of Selsura-7 series (very shallow), others are moderately or marginally suitable for one or more commonly growing rainfed kharif crops viz. cotton, sorghum, pigeonpea, soybean and groundnut.
  • Authors:
    • Aiken, R. M.
    • Currie, R. S.
    • Klocke, N. L.
  • Source: Transactions of the ASABE
  • Volume: 52
  • Issue: 1
  • Year: 2009
  • Summary: Crop residues have value when left in the field and also when removed from the field and sold as a commodity. Reducing soil water evaporation (E) is one of the benefits of leaving crop residues in place. E was measured beneath a maize canopy at the soil surface with nearly full coverage by maize stover or standing wheat stubble. E was also measured from a soil surface that was partially covered with corn stover without crop shading. E was measured with mini-lysimeters that were 300 mm in diameter and 140 mm deep. Surface coverage and amount of dry matter of crop residues influenced E. E was reduced nearly 50% compared with bare soil E when maize stover and wheat stubble nearly covered the surface under a maize canopy during the growing season. Partial surface coverage, from 25 to 75%, with corn stover caused small reductions in E compared with bare soil when there was no crop canopy. Full surface coverage reduced energy limited E 50 to 65% compared with E from bare soil with no shading. No-till management, using crop residues to significantly reduce E, required soil surfaces to be nearly covered. Economic benefits of crop residues for E suppression during the growing season can be as much as $365 ha -1.
  • Authors:
    • Takle, S. R.
    • Kunte, A. P.
    • Bhise, V. B.
  • Source: Resource-use efficiency in irrigated Indian agriculture 2009
  • Year: 2009
  • Summary: The present study was conducted on irrigated farms to study the resource use efficiency and returns to scale in the command area of Penganga irrigation project. A sample of 310 farmers was scientifically chosen out of which 94 were from head-reach, 100 from middle reach and 116 belonged the tail reach location of the command area and the study was conducted during the agricultural year 2004-05. The study was confined to three foodgrains, i.e. green gram, kharif Jowar and Wheat, and four cash crops, viz., cotton, sugarcane, banana and soyabean. A Cobb-Douglas production function was fitted to estimate the resource-use efficiency and returns to scale in the crop production in irrigated Indian agriculture. The study observed that some of the resources have been either under-utilised or over-utilised; hence to increase the agricultural production all the resources should be used efficiently. Along with the efficient use of all the resources, new technology should also be adopted for increasing productivity. The ratio of marginal value product to factor cost for some resources (human labour, bullock labour, fertilisers and seeds) was found to be more than one, indicating the operation of increasing factors returns. In general for cash crops, the study suggests to increase the use of resources viz. bullock labour, working capital, seeds and irrigation so as to increase the production of the cultivated cash crops.
  • Authors:
    • Kushwaha, S. S.
    • Gajja, B. L.
  • Source: Current Agriculture
  • Volume: 33
  • Issue: 1/2
  • Year: 2009
  • Summary: An attempt has been made to document the change in the cropping pattern in Rajasthan, India. The study was based on the secondary data from 1980-81 to 2006-07. There was no major change in the cropping pattern, but in some crops such as rape, mustard and soyabean a shift was recorded. The increase in irrigation facilities in the state had observed increase in irrigated crops such as cotton, groundnut in some parts, wheat, soyabean, rape and mustard while some crops had witnessed the reduction in area. This indicated some minor change in the cropping pattern. However, the cropping pattern was mainly influenced by physical, economic, technological and institutional factors such as capital and market location and price of the crop at harvest time had definite temporal changes. The crop diversification had been witnessed in favour of oilseed crops.
  • Authors:
    • Priess, J. A.
    • Lapola, D. M.
    • Bondeau, A.
  • Source: Biomass and Bioenergy
  • Volume: 33
  • Issue: 8
  • Year: 2009
  • Summary: The governments of Brazil and India are planning a large expansion of bioethanol and biodiesel production in the next decade. Considering that limitation of suitable land and/or competition with other land uses might occur in both countries, assessments of potential crop productivity can contribute to an improved planning of land requirements for biofuels under high productivity or marginal conditions. In this paper we model the potential productivity of sugarcane and jatropha in both countries. Land requirements for such expansions are calculated according to policy scenarios based on government targets for biofuel production in 2015. Spatial variations in the potential productivity lead to rather different land requirements, depending on where plantations are located. If jatropha is not irrigated, land requirements to fulfill the Indian government plans in 2015 would be of 410 000 to 95 000 km 2 if grown in low or high productivity areas respectively (mean of 212 000 km 2). In Brazil land requirements, are of 18 000-89 000 km 2 (mean of 29 000 km 2), suggesting a promising substitute to soybean biodiesel. Although future demand for sugarcane ethanol in Brazil is approximately ten times larger than in India, land requirements are comparable in both countries due to large differences in ethanol production systems. In Brazil this requirement ranges from 25 000 to 211 000 km 2 (mean of 33 000 km 2) and in India from 7000 to 161 000 km 2 (mean 17 000 km 2). Irrigation could reduce the land requirements by 63% and 41% (24% and 15%) in India (Brazil) for jatropha and sugarcane respectively.
  • Authors:
    • Hunt, T. E.
    • Magalhaes, L. C.
    • Siegfried, B. D.
  • Source: Journal of Economic Entomology
  • Volume: 102
  • Issue: 1
  • Year: 2009
  • Summary: The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is native to Asia and was recently (2000) detected in North America. Since then, it has become a significant threat to U.S. soybean production. Although neonicotinoid insecticide seed treatments, imidacloprid and thiamethoxam, have been suggested as a method of control, the season-long efficacy is still uncertain. Therefore, the use of imidacloprid and thiamethoxam seed treatments to control soybean aphid in Nebraska were examined. Soybean aphid populations were monitored weekly in an irrigated field study planted during the later half of the typical Nebraska planting window during 2005 and 2006. Imidacloprid and thiamethoxam were quantified by leaves through time, and leaf specific bioassays were conducted. In 2005, aphid populations were very low; however, in 2006 aphid numbers were significantly higher than 2005, reaching ~1,200 aphids per plant in the untreated plots. Aphid injury significantly reduced yield and individual seed size in 2006. Imidacloprid significantly reduced aphid densities in 2006 but not below the economic threshold. In 2006, thiamethoxam held aphid densities below the economic threshold. Leaf specific bioassays and leaf specific imidacloprid and thiamethoxam quantification indicated that thiamethoxam was present in the plant at higher concentrations and for a longer period.