751. Nitrogen fixation of red clover interseeded with winter cereals across a management-induced fertility gradient

• Authors:
  • Drinkwater, L. E.
  • Schipanski, M. E.
• Source: Nutrient Cycling in Agroecosystems
• Volume: 90
• Issue: 1
• Year: 2011
• Summary: The incorporation of legume cover crops into annual grain rotations remains limited, despite extensive evidence that they can reduce negative environmental impacts of agroecosystems while maintaining crop yields. Diversified grain rotations that include a winter cereal have a unique niche for interseeding cover crops. To understand how management-driven soil fertility differences and inter-seeding with grains influenced red clover (Trifolium pratense) N(2) fixation, we estimated biological N(2) fixation (BNF) in 2006 and 2007, using the (15)N natural abundance method across 15 farm fields characterized based on the reliance on BNF derived N inputs as a fraction of total N inputs. Plant treatments included winter grain with and without interseeded red clover, monoculture clover, monoculture orchardgrass (Dactylis glomerata), and clover-orchardgrass mixtures. Fields with a history of legume-based management had larger labile soil nitrogen pools and lower soil P levels. Orchardgrass biomass was positively correlated with the management-induced N fertility gradient, but we did not detect any relationship between soil N availability and clover N(2) fixation. Interseeding clover with a winter cereal did not alter winter grain yield, however, clover production was lower during the establishment year when interseeded with taller winter grain varieties, most likely due to competition for light. Interseeding clover increased the % N from fixation relative to the monoculture clover (72% vs. 63%, respectively) and the average total N(2) fixed at the end of the first growing season (57 vs. 47 kg N ha(-1), respectively). Similar principles could be applied to develop more cash crop-cover crop complementary pairings that provide both an annual grain harvest and legume cover crop benefits.

752. Cover crop effects on nitrogen load in tile drainage from Walnut Creek Iowa using root zone water quality (RZWQ) model

• Authors:
  • Jaynes, D. B.
  • Malone, R. W.
  • Singer, J. W.
  • Ma, L.
• Source: Agricultural Water Management
• Volume: 98
• Issue: 10
• Year: 2011
• Summary: Studies quantifying winter annual cover crop effects on water quality are mostly limited to short-term studies at the plot scale. Long-term studies scaling-up water quality effects of cover crops to the watershed scale provide more integrated spatial responses from the landscape. The objective of this research was to quantify N loads from artificial subsurface drainage (tile drains) in a subbasin of the Walnut Creek, Iowa (Story county) watershed using the hybrid RZWQ-DSSAT model for a maize (Zen mays L.)soybean [Glycine max (L.) Merr.] and maize-maize-soybean rotations in all phases with and without a winter wheat (Triticum aestivum L.) cover crop during a 25-year period from 1981 to 2005. Simulated cover crop dry matter (DM) and N uptake averaged 1854 and 36 kgha(-1) in the spring in the maize-soybean phase of the 2-year rotation and 1895 and 36 kg ha(-1) in the soybean-maize phase during 1981-2005. In the 3-year rotation, cover crop DM and N uptake averaged 2047 and 44 kg ha(-1) in the maize-maize-soybean phase, 2039 and 43 kg ha(-1) in the soybean-maize-maize phase. and 1963 and 43 kg ha(-1) in the maize-soybean-maize phase during the same period. Annual N loads to tile drains averaged 29 kg ha(-1) in the maize-soybean phase and 25 kg ha(-1) in the soybean-maize phase compared to 21 and 20 kg ha(-1) in the same phases with a cover crop. In the 3-year rotation. annual N loads averaged 46, 43, and 45 kg ha(-1) in each phase of the rotation without a cover crop and 37, 35, and 35 kg ha(-1) with a cover crop. These results indicate using a winter annual cover crop can reduce annual N loads to tile drains 20-28% in the 2-year rotation and 19-22% in the 3-year rotation at the watershed subbasin scale over a 25-year period. Published by Elsevier B.V.

753. Cropping pattern of Uttar Pradesh using IRS-P6 (AWiFS) data

• Authors:
  • Jain, K.
  • Kudrat, M.
  • Singh, N. J.
  • Pandey, K.
• Source: International Journal of Remote Sensing
• Volume: 32
• Issue: 16
• Year: 2011
• Summary: The cropping pattern (rotation) of a region depends on the soil, water availability, economic conditions and climatic factors. Remote sensing is one of the effective tools that can provide precise and up-to-date information on the performance of agricultural systems. Four seasons data from the Indian Remote Sensing Satellite (IRS)-P6 Advanced Wide Field Sensor (AWiFS) were used for the generation of the cropping pattern of Uttar Pradesh by geographic information system (GIS)-aided integration of digitally classified crop and land use inventories of the kharif, rabi and zaid crop seasons. Twelve different cropping patterns were delineated and mapped in the Indo-Gangetic plain of Uttar Pradesh. The forests covered about 6.32% of the total geographical area. The net cropped area was 20 282 159.46 ha (84.18% of the total geographical area) and the non-agricultural area observed was 3 437 376.00 ha (14.26% of the total geographical area). Rice was the single most dominant crop of the state, occupying about 32.94% of the total geographical area during the kharif season. Maize/jowar was the second major cereal crop, accounting for 13.77% of the total geographical area of the state. The major crops grown during the rabi season were wheat and pulses/oilseed, covering areas of 7 979 267.71 ha (33.12%) and 5 974 742.58 ha (24.80%), respectively. Rice-wheat, sugarcane and rice-pulses were the major cropping patterns, occupying about 3 958 739.85 ha (16.43%), 3 609 939.74 ha (14.98%) and 2 511 298.24 ha (10.42%), respectively. The areas under pulses/oilseed were significantly higher in the rabi season. Sugarcane-wheat and pulses shared an almost equal area (6.49%). The maize/jowar-wheat cropping pattern occupied 6.14% of the total geographical area of the state. Single cropping patterns (i.e. rice-fallow, fallow-pulses, fallow-wheat, maize-fallow and sugarcane-fallow) were minor, occupying 6.08, 2.94, 4.06, 2.69 and 2.51%, respectively. Waste land, including gulley, salt-affected, waterlogged and rock land, accounted for 3.80% of the total geographical area. The results of this study indicate that temporal IRS-P6 (AWiFS) data are very useful for studying spatial cropping patterns. The values of the Multiple Cropping Index (MCI) and the Cultivated Land Utilization Index (CLUI) show that the study area has a high cropping intensity.

754. 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.

755. The influence of a long-term black medic (Medicago lupulina cv. George) cover crop on arbuscular mycorrhizal fungal colonization and nutrient uptake in flax (Linum usitatissimum) under zero-tillage management

• Authors:
  • LaFond, G. P.
  • May, W. E.
  • Tenuta, M.
  • Entz, M. H.
  • Turmel, M. S.
• Source: Canadian Journal of Plant Science
• Volume: 91
• Issue: 6
• Year: 2011
• Summary: Leguminous cover crops are becoming a popular way to increase the sustainability of agricultural systems. Previously, cover crops have been found to increase colonization by arbuscular mycorrhizal fungi (AM F) and phosphorus and micronutrient uptake. Long-term field studies were conducted to test the hypothesis that self-regenerating black medic (Medicago lupulina cv. George) cover crops increase AM F colonization and early nutrient uptake in flax (Linum usitatissimum). Field experiments were established in 2000 (Manitoba) and 2002 (Saskatchewan) using a flax wheat (Triticum aestivum) oat (Avena sativa) rotation. In a second experiment, intact soil cores were harvested from the plots in spring and tested for soil disturbance and cover crop effects under controlled environment conditions (CEC). Both seedling flax crops sampled from the field in 2005 and 2006 and flax growth in CEC showed high levels of AMF root colonization, but no significant influence of the cover crop on AM F colonization by arbuscules or hyphal structures was detected. The AMF enhancing practices used in the experiments (i.e., zero-tillage and inclusion of mycorrhizal crops) may have contributed to the lack of cover crop effect on AMF colonization. The cover crop had no effect on macro- or micronutrient uptake by flax except during drought conditions (Winnipeg 2006), where flax biomass was reduced by 38% and the total uptake of N, P, Zn and Cu was decreased by 34, 30, 31 and 35%, respectively, in the medic treatment.

756. Water use and yield of wheat/maize intercropping under alternate irrigation in the oasis field of northwest China.

• Authors:
  • Chai, Q.
  • Huang, G. B.
  • Yang, C. H.
  • Luo, Z. X.
• Source: Field Crops Research
• Volume: 124
• Issue: 3
• Year: 2011
• Summary: A field experiment was carried out to investigate the effects of alternate irrigation (AI) on the yield, water use and water use efficiency (WUE) of wheat (Triticum aestivum L.)/maize (Zea mays L.) intercropping system in an oasis region of northwest China in 2006-2008. Three planting patterns, i.e., sole wheat, sole maize and wheat/maize intercropping. Three irrigation levels were applied for each treatment during 3 years. Results showed that land use efficiency of wheat and maize was significantly enhanced by intercropping system; land equivalent ratio (LER) of wheat/maize intercropping system in different treatments was all greater than 1.0. Moreover, significant difference in grain yield was observed between intercropping treatment and sole cropping treatment, in which the yield of intercropped wheat was 55.37-74.88% of sole wheat, and intercropped maize was 66.63-78.87% of sole maize. Wheat/maize intercropping treatments increased water use by 1.8-16.4% than half of the total water use of sole-cropping wheat and maize. Compared to sole cropping wheat treatments, wheat/maize intercropping with alternate irrigation significantly improved water use efficiency (WUE) by 30.5-57.7%, 55.5-71.4% and 12.0-19.8%, and increased by 32.7-37.8%, 9.5-15.8% and 4.0-20.8% than sole cropping maize treatments in 2006-2008, respectively. Our results suggest that AI should be a useful water-saving irrigation method on wheat/maize intercropping in arid oasis field where intercropping planting is decreased because of limited water resource.

757. 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.

758. Water use characteristics of alternately irrigated wheat/maize intercropping in oasis region of northwestern China.

• Authors:
  • Huang, G. B.
  • Yang, C. H.
  • Chai, Q.
• Source: ACTA AGRONOMICA SINICA
• Volume: 37
• Issue: 9
• Year: 2011
• Summary: In oasis irrigation region of northwestern China, the decreasing of multiple cropping areas may lead to significant reduction of land and light use efficiencies due to serious water shortage. Therefore, water-saving irrigation is a priority in the research on theory and technology for intercropping system. Alternate irrigation is a technique to save water and enhance water use efficiency (WUE) simultaneously in common cropping systems. However, its effect is not clear on intercropping system. In 2006-2008 cropping years, we carried out a field experiment in oasis region of Hexi Corridor, Gansu province, China under wheat/maize intercropping to disclose the effects of alternate irrigation on crop yields, water consumption, and WUE. The results showed that, compared to sole cropping treatments, there was a significant increase of land equivalent ratio (LER) in the alternately irrigated wheat/maize intercropping treatment with the LER values ranging from 1.22 to 1.52 under different irrigation levels of the intercropping treatments. However, the difference of LERs between conventionally irrigated and alternately irrigated intercropping systems was not significant at the same irrigation quota. Compared to the conventionally irrigated intercropping treatment, there was no significant change of wheat yield in the alternately irrigated intercropping treatment, but significant increase by 11.4-36.4% in maize yield. Therefore, the total yield of wheat and maize in the alternately irrigated intercropping treatment was increased by 12.9 averagely. The water consumption in the alternately irrigated intercropping treatment had no significant increase compared to that of the conventionally irrigated intercropping treatment, with 1.2-19.4% higher than the weighted average of monoculture of both crops. The WUE of alternately irrigated intercropping treatment was 0.9-22.5% higher than that of the conventionally irrigated intercropping treatment, and 12.0-71.4% and 10.6-37.8% higher than that of wheat and maize monoculture, respectively. These results suggest that alternate irrigation is feasible in intercropping systems in arid oasis regions with the purpose of saving water and increasing WUE.

759. Soil evaporation under sole cropping and intercropping systems and the main driving factors.

• Authors:
  • Huang, P.
  • Chen, G. P.
  • Yu, A. Z.
  • Chai, Q.
• Source: Chinese Journal of Eco-Agriculture
• Volume: 19
• Issue: 6
• Year: 2011
• Summary: Several studies have shown that compared to sole cropping, well managed intercropping improves agricultural resources utilization efficiency, include radiation, nutrient, water and land. However, high productivity of traditional intercropping system has mainly depended on high input of agricultural resources. With severe water shortages in recent years (especially in mainland China), intercropping system of farming has continuously declined. The scientific challenge therefore is the determination of water consumption characteristics and systematic development of high-efficiency water-saving theories and technologies of intercropping system. In this study, a field experiment (comprising of wheat or maize sole cropping and wheat-maize intercropping systems under three different irrigation schemes) was conducted in 2008 in the Hexi Corridor oasis region. The study investigated soil evaporation characteristics and associated driving factors under the different cropping systems and treatments with the aim of laying the scientific basis for developing optimized irrigation techniques. The study showed that evapotranspiration ( ET) under wheat-maize intercropping was 41.44%-47.15% higher than the average ET under wheat and maize sole cropping systems. Total soil evaporation ( E) of intercropping system was significantly higher than that of sole cropping systems. However, daily E of intercropping system was significantly lower than that of maize sole cropping system. Also compared with sole cropping system of maize, wheat-maize intercropping system enhanced E/ET ratio. With increasing irrigation, total water consumption increased significantly under intercropping. However, the difference in water consumption between two adjacent irrigation treatments under sole cropping systems of wheat and maize was insignificant. The difference in E of sole cropping maize and intercropping wheat-maize was insignificant for different irrigation schemes. It then implied that high water consumption of intercropping system was mainly driven by high transpiration. Average daily E was positively correlated with water content in the 0-30 cm soil profile, temperature in the 0-25 cm soil profiles and average leaf area index of the crops. High E was driven by high water content in the 0-30 cm soil profile and temperature in the 0-25 cm soil profile of maize sole cropping system. On the average, wheat-maize intercropping not only reduced water consumption but also increased water and land use efficiency compared to sole cropping. This cut down wasteful crop transpiration, which was an effective means of water-saving irrigation.

760. Spatial and seasonal distribution of nitrate-N in groundwater beneath the rice-wheat cropping system of India: a geospatial analysis

• 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.