Interspecific competition,N use and interference with weeds in pea–barley intercropping     

《Field Crops Research》2001,70(2):101-109

Field pea (Pisum sativum L.) and spring barley (Hordeum vulgare L.) were intercropped and sole cropped to compare the effects of crop diversity on productivity and use of N sources on a soil with a high weed pressure. ¹⁵N enrichment techniques were used to determine the pea–barley–weed-N dynamics. The pea–barley intercrop yielded 4.6 t grain ha⁻¹, which was significantly greater than the yields of pea and barley in sole cropping. Calculation of land equivalent ratios showed that plant growth factors were used from 25 to 38% more efficiently by the intercrop than by the sole crops. Barley sole crops accumulated 65 kg soil N ha⁻¹ in aboveground plant parts, which was similar to 73 kg soil N ha⁻¹ in the pea–barley intercrop and significantly greater than 15 kg soil N ha⁻¹ in the pea sole crop. The weeds accumulated 57 kg soil N ha⁻¹ in aboveground plant parts during the growing season in the pea sole crops. Intercropped barley accumulated 71 kg N ha⁻¹. Pea relied on N₂ fixation with 90–95% of aboveground N accumulation derived from N₂ fixation independent of cropping system. Pea grown in intercrop with barley instead of sole crop had greater competitive ability towards weeds and soil inorganic N was consequently used for barley grain production instead of weed biomass. There was no indication of a greater inorganic N content after pea compared to barley or pea–barley. However, 46 days after emergence there was about 30 kg N ha⁻¹ inorganic N more under the pea sole crop than under the other two crops. Such greater inorganic N levels during early growth phases was assumed to induce aggressive weed populations and interspecific competition. Pea–barley intercropping seems to be a promising practice of protein production in cropping systems with high weed pressures and low levels of available N.  相似文献   

Interactions between non-flooded mulching cultivation and varying nitrogen inputs in rice–wheat rotations     

《Field Crops Research》2005,91(2-3):307-318

A 3-year field experiment examined the effects of non-flooded mulching cultivation and traditional flooding and four fertilizer N application rates (0, 75, 150 and 225 kg ha⁻¹ for rice and 0, 60,120, and 180 kg N ha⁻¹ for wheat) on grain yield, N uptake, residual soil N_min and the net N balance in a rice–wheat rotation on Chengdu flood plain, southwest China. There were significant grain yield responses to N fertilizer. Nitrogen applications of >150 kg ha⁻¹ for rice and >120 kg ha⁻¹ for wheat gave no increase in crop yield but increased crop N uptake and N balance surplus in both water regimes. Average rice grain yield increased by 14% with plastic film mulching and decreased by 16% with wheat straw mulching at lower N inputs compared with traditional flooding. Rice grain yields under SM were comparable to those under PM and TF at higher N inputs. Plastic film mulching of preceding rice did not affect the yield of succeeding wheat but straw mulching had a residual effect on succeeding wheat. As a result, there was 17–18% higher wheat yield under N0 in SM than those in PM and TF. Combined rice and wheat grain yields under plastic mulching was similar to that of flooding and higher than that of straw mulching across N treatments. Soil mineral N (top 60 cm) after the rice harvest ranged from 50 to 65 kg ha⁻¹ and was unaffected by non-flooded mulching cultivation and N rate. After the wheat harvest, soil N_min ranged from 66 to 88 kg N ha⁻¹ and increased with increasing fertilizer N rate. High N inputs led to a positive N balance (160–621 kg ha⁻¹), but low N inputs resulted in a negative balance (−85 to −360 kg ha⁻¹). Across N treatments, the net N balances of SM were highest among the three cultivations systems, resulting from additional applied wheat straw (79 kg ha⁻¹) as mulching materials. There was not clear trend found in net N balance between PM and TF. Results from this study indicate non-flooded mulching cultivation may be utilized as an alternative option for saving water, using efficiently straw and maintaining or improving crop yield in rice–wheat rotation systems. There is the need to evaluate the long-term environmental risks of non-flooded mulching cultivation and improve system productivity (especially with straw mulching) by integrated resource management.  相似文献   

Will nutrient-efficient genotypes mine the soil? Effects of genetic differences in root architecture in common bean (Phaseolus vulgaris L.) on soil phosphorus depletion in a low-input agro-ecosystem in Central America     

Amelia Henry  Nestor F. Chaves  Peter J.A. Kleinman  Jonathan P. Lynch 《Field Crops Research》2010,115(1):67-78

Crop genotypes with root traits permitting increased nutrient acquisition would increase yields in low fertility soils but have uncertain effects on soil fertility in the long term because of competing effects on nutrient removal vs. the soil conserving effects of greater crop biomass. This study evaluated the relative importance of phosphorus loss in crop extraction vs. phosphorus loss in soil erosion as influenced by genetic differences in root shallowness and therefore phosphorus uptake in common bean (Phaseolus vulgaris L.). Six recombinant inbred lines of varying root architecture and two commercial genotypes of bean were grown in unfertilized, steeply sloped (32%), low phosphorus (5.8 mg kg^?1, Fe-strip) Udults in Costa Rica. Fertilized (60 kg total phosphorus ha^?1) plots of commercial genotypes were also included in the study. Runoff was monitored throughout the bean growing season in 2005 and 2006, and in 2006, monitoring continued through the maize growing season. Phosphorus removed in plant biomass at harvest through the 2006 bean–maize crop cycle averaged 7.3 kg ha^?1 year^?1, greatly exceeding phosphorus loss due to erosion (0.15–0.53 kg ha^?1 year^?1) in unfertilized plots. In fertilized bean plots, total biomass phosphorus averaged 6.32 kg ha^?1 year^?1 and total eroded phosphorus averaged 0.038 kg ha^?1 year^?1, indicating rapid sorption of fertilizer phosphorus. Shoot growth of several recombinant inbred lines under low phosphorus was comparable to that of fertilized commercial genotypes, illustrating the effectiveness of selection for root traits for improving plant growth in low-phosphorus soils. Genotypic differences in root architecture of recombinant inbred lines led to 20–50% variation in groundcover by shoots, which was associated with 50–80% reduction in sediment loss. This study demonstrates that root architecture traits can affect nutrient cycling at the agro-ecosystem level, and that integrated nutrient management strategies are necessary to avoid soil nutrient depletion.  相似文献   

Effects of soil water content and nitrogen supply on the productivity of Miscanthus × giganteus Greef et Deu. in a Mediterranean environment     

《Industrial Crops and Products》2007,25(1):75-88

Miscanthus × giganteus is one of the most promising biomass crops for non-food utilisation. Taking into account its area of origin (Far East), its temperature and rainfall requirements are not well satisfied in Mediterranean climate. For this purpose, a research was carried out with the aim of studying the adaptation of the species to the Mediterranean environment, and at analysing its ecophysiological and productive response to different soil water and nitrogen conditions. A split plot experimental design with three levels of irrigation (I₁, I₂ and I₃ at 25%, 50% and 100% of maximum evapotranspiration (ETm), respectively) and three levels of nitrogen fertilisation (0 kg ha⁻¹: N₀, 60 kg ha⁻¹: N₁ and 120 kg ha⁻¹: N₂ of nitrogen) were studied. The crop showed a high yield potential under well-watered conditions (up to 27 t ha⁻¹ of dry matter). M. × giganteus, in Mediterranean environment showed a high yield potential even in very limited water availability conditions (more than 14 t ha⁻¹ with a 25% ETm restoration). A responsiveness to nitrogen supply, with great yield increases when water was not limiting, was exhibited. Water use efficiency (WUE) achieved the highest values in limited soil water availability (between 4.51 and 4.83 g l⁻¹), whilst in non-limiting water conditions it decreased down to 2.56 and 3.49 g l⁻¹ (in the second and third year of experiment, respectively). Nitrogen use efficiency (NUE) decreased with the increase of water distributed (from 190.5 g g⁻¹ of I₀ to 173.2 g g⁻¹ of I₂); in relation to N fertilisation it did not change between the N fertilised treatments (N₁ and N₂), being much higher in the unfertilised control (177.1 g g⁻¹). Radiation use efficiency (NUE) progressively declined with the reduction of the N fertiliser level (1.05, 0.96 and 0.86 g d.m. MJ⁻¹, in 1994, and 0.92, 0.91 and 0.69 g d.m. MJ⁻¹, in 1995, for N₂, N₁ and N₀, respectively).  相似文献   

Effects of N application on agronomic and environmental parameters in silage maize production on sandy soils     

《Field Crops Research》1998,58(1):55-67

The current nitrogen (N) use in silage maize production can lead to considerable N losses to the environment. Maize growers fear that a reduction of N inputs needed to minimize N losses might depress yields. The objective of this study was therefore to quantify: (1) the response of silage maize dry matter (DM) yields to N, (2) the economically optimal N reserve, and (3) the trade-off between silage maize DM yield and N losses. The indicators of N losses used in this study were the difference between N input and N uptake and the post-harvest residual soil mineral N. Regression models were used to fit DM yields and N uptakes of silage maize measured in 25 experiments on sandy soils in the Netherlands to the sum (SUMN) of the soil mineral N reserve (SMN_early) in March–April, plus mineral N in fertilizer, plus ammonium N in spring-applied slurry. The values obtained for the economically optimal SUMN in the upper 30 and 60 cm of soil were, respectively, 173 and 195 kg N ha⁻¹, when we assumed that the value of 1 kg fertilizer N equals the value of 5 kg silage DM. The economically optimal SUMN was not significantly related to the attainable DM yield. The apparent N recovery (ANR) of maize averaged 53% at the economically optimal SUMN. The ANR rose considerably, however, when N was applied at lower rates, indicating that N losses may be considerably smaller in less intensive maize cropping. When maize was fertilized at 100 kg N ha⁻¹ below the economic optimum, the ANR was 73%, the difference between the mineral N input and the N crop uptake decreased by 57 kg N ha⁻¹ and the soil mineral N residue at the end of the growing season (0–60 cm) decreased by 24 kg N ha⁻¹. The associated reduction in DM yield averaged 16%. Fertilizer prices would have to be as much as four times higher to make maize growers spontaneously reduce the application rates by a 100 kg N ha⁻¹, however. It is concluded that adjusting the N input to a level below the economically optimal rate can reduce the risks for N losses to the environment associated with conventional maize production, with a limited effect on silage yields.  相似文献   

Influence of irrigation frequency on greenhouse gases emission from a paddy soil     

S. C. Maris  M. R. Teira-Esmatges  M. M. Català 《Paddy and Water Environment》2016,14(1):199-210

Water management is known to be a key factor on methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) emissions from paddy soils. A field experiment was conducted to study the effect of continuous irrigation (CI) and intermittent irrigation (II) on these emissions. Methane, CO₂, and N₂O emissions from a paddy soil were sampled weekly using a semi-static closed chamber and quantified with the photoacoustic technique from May to November 2011 in Amposta (Ebro Delta, NE Spain). Intermittent irrigation of rice paddies significantly stimulated (N₂O + N₂)–N emission, whereas no substantial N₂O emission was observed when the soil was re-wetted after the dry phase. The cumulative emission of (N₂O + N₂)–N was significantly larger from the II plots (0.73 kg N₂O–N ha^?1 season^–1, P < 0.05) than from the CI plots (?1.40 kg N₂O–N ha^?1 season^?1). Draining prior to harvesting increased N₂O emissions. Draining and flooding cycles controlled CO₂ emission. The cumulative CO₂ emission from II was 8416.35 kg CO₂ ha^?1 season^?1, significantly larger than that from CI (6045.26 kg CO₂ ha^?1 season^?1, P < 0.05). Lower CH₄ emission due to water drainage increased CO₂ emissions. The soil acted as a sink of CH₄ for both types of irrigation. Neither N₂O–N nor CH₄ emissions were affected by soil temperature. Global warming potential was the highest in II (4738.39 kg CO₂ ha^?1) and the lowest in CI (3463.41 kg CO₂ ha^?1). These findings suggest that CI can significantly mitigate the integrative greenhouse effect caused by CH₄ and N₂O from paddy fields while ensuring the highest rice yield.  相似文献   

Model predictions of winter rainfall effects on N dynamics of winter wheat rotation following legume cover crop or fallow     

《Field Crops Research》2005,91(2-3):251-261

Winter rainfall in a Mediterranean region varies from year to year. Both release of inorganic N from soil organic matter (SOM) or a legume cover crop (LCC) and subsequent nitrate movement in the soil profile are strongly affected by winter rainfall, through its effects on soil water status and on vertical flux. N accumulation of a LCC also varies over years due to weather effects on growth. Thus, these two factors need to be taken into account for efficient use of SOM-N and LCC-N in a wheat (Triticum aestivum L.) rotation. To determine how winter weather might affect the performance of wheat-fallow rotations that include an LCC grown and incorporated during the fallow year, we used the CERES-wheat model and a 46-season weather record to simulate N dynamics of 2-year unfertilized and irrigated winter-LCC wheat systems with high LCC (236 kg N ha⁻¹) or low LCC (118 kg N ha⁻¹) inputs. Unfertilized and fertilized fallow-wheat controls were also simulated. Within a given LCC input value, coefficients of variation for total seasonal N supply (the sum of predicted wheat N uptake, N leaching and inorganic soil N at wheat maturity) over years were <15%, despite the fluctuating winter rainfall (CV 48%). Average N leaching was predicted to be highest in the high LCC input system (108 kg N ha⁻¹), followed by the low LCC input system (86 kg N ha⁻¹) and midseason-intensive and planting-intensive fertilized wheat-fallow systems (82 and 72 kg N ha⁻¹, respectively), and least in the unfertilized wheat-fallow system (54 kg N ha⁻¹). N leaching exceeded 100 kg N ha⁻¹ in 4, 20, 16, 18, and 29 seasons out of 46 seasons, respectively, in the unfertilized and planting-intensive and midseason-intensive fertilized wheat-fallow rotations and in wheat rotations with low and high LCC inputs. There was no difference in predicted wheat yield among the four systems with N inputs from fertilizer or LCC, but yield was lower in the unfertilized wheat-fallow rotation. If the goal of use of LCC was to attain the same yield level as high LCC input or fertilized wheat system while diminishing the risk of N leaching, the low LCC input case met this goal in the short term. However, a simple balance sheet using the model showed that the N balance of the low LCC input system was −147 kg N ha⁻¹ season⁻¹, if we assumed 50% of LCC-N was derived from atmospheric fixation. The low-LCC-input system could therefore fail to maintain inherent soil N fertility in the long term unless nearly 100% LCC-N was derived from fixation.  相似文献   

Strategies for overcoming low agronomic nitrogen use efficiency in irrigated rice systems in China     

《Field Crops Research》2006,96(1):37-47

Irrigated rice in China accounts for nearly 30% of global rice production and about 7% of global nitrogen (N) consumption. The low agronomic N use efficiency (AE_N, kg grain yield increase per kg N applied) of this system has become a threat to the environment. The objective of this study was to determine the possibility to improve the AE_N of irrigated rice in China by comparing the farmers’ N-fertilizer practices with other N management strategies such as real-time N management (RTNM) and fixed-time adjustable-dose N management (FTNM). Field experiments were conducted in farmers’ fields in four major rice-growing provinces in China in 2001 and 2002. The same experiment was repeated at the International Rice Research Institute (IRRI) farm in the dry seasons of 2002 and 2003. Agronomic N use efficiency was determined by the “difference method” using an N-omission plot. Maximum yield was achieved mostly at 60–120 kg N ha⁻¹, which was significantly lower than the 180–240 kg N ha⁻¹ applied in farmers’ practices at the Chinese sites. With the modified farmers’ fertilizer practice, a 30% reduction in total N rate during the early vegetative stage did not reduce yield but slightly increased yield and doubled AE_N compared with the farmers’ practice at the Chinese sites. The total N rate in RTNM and FTNM ranged from 30 to 120 kg ha⁻¹ at the Chinese sites, but their yields were similar to or higher than that of the farmers’ practice. Compared with the modified farmers’ practice, RTNM and FTNM further increased AE_N at the Chinese sites. Overall, FTNM performed better than RTNM at the Chinese sites because the total N rate of FTNM was closer to the optimal level than RTNM. A quantum leap in AE_N is possible in the intensive rice-growing areas in China by simply reducing the current N rate and by allocating less N at the early vegetative stage.  相似文献   

Effect of N rate,timing and splitting and N type on bread-making quality in hard red spring wheat under rainfed Mediterranean conditions     

《Field Crops Research》2004,85(2-3):213-236

Three different experiments were designed to study the effects of N fertilizer rate, timing and splitting, and the response to combined application of N and S fertilizer on the bread-making quality of hard red spring wheat (Triticum aestivum L.) over a 3-year period in Vertisols under rainfed Mediterranean conditions. The following parameters were analyzed: grain yield, test weight, grain protein content, gluten index and alveograph parameters (W: alveogram index; P: dough tenacity; L: dough extensibility; P/L: tenacity–extensibility ratio). The N rate experiment included rates of 0, 100, 150 and 200 kg N ha⁻¹ applied on four different sites. The experiment was designed as a randomized complete block with four blocks. For the experiment on N timing and splitting, a single rate of 150 kg N ha⁻¹ was used, different fractions being applied at sowing, tillering and stem elongation, at a single site; again, experimental design was a randomized complete block with four blocks. Finally, for the experiment on the response to combined application of N and S fertilizer, a single fertilizer dose of 150 kg N ha⁻¹ was applied in two forms (urea+ammonium nitrate and urea+ammonium nitrosulfate) with one leaf application at ear emergence (zero, 25 kg S ha⁻¹, 25 kg N ha⁻¹, $\text{25}\text{kg}\text{S}\text{ha}{}^{\mathrm{-1}}\text{+25}$ kg N ha⁻¹ and 50 kg N ha⁻¹), also at a single site, using a split-plot design with four replications. Year-on-year variation in rainfall led to marked variations in wheat yield, grain protein content and bread-making quality indices. A close correlation was observed between rainfall over the September–May period and both grain yield and grain protein content (optimum values for both being recorded in the rainfall range 500–550 mm) as well as the alveogram index. A negative correlation was observed between mean maximum temperatures in May and both test weight and alveogram index (W). N fertilizer rate had a more consistent effect on bread-making quality than on grain yield. The highest values for grain yield were recorded at an N rate of 100 kg ha⁻¹, while maximum grain protein content values were recorded at 150 kg ha⁻¹. Application of half or one-third of total fertilizer N at stem elongation improved grain yield and grain protein content with respect to applications at sowing alone or at both sowing and tillering. Increased N rates led to a considerable increase in W values and to a reduction in the P/L ratio, thus improving dough balance, with a negative effect on the gluten index. Leaf application of N at ear emergence only affected grain protein content and the W index. Soil or leaf application of S had no effect on protein quality indices. The response of grain yield and grain protein content to fertilizer N differed from that reported for temperate climates.  相似文献   

Using legumes to enhance nitrogen fertility and improve soil condition in cotton cropping systems     

《Field Crops Research》2001,70(1):27-41

Many Australian cotton growers now include legumes in their cropping system. Three experiments were conducted between 1994 and 1997 to evaluate the rotational effects of winter or summer legume crops grown either for grain or green manuring on following cotton (Gossypium hirsutum L.). Non-legume rotation crops, wheat (Triticum aestivum) and cotton, were included for comparison. Net nitrogen (N) balances, which included estimates of N associated with the nodulated roots, were calculated for the legume phase of each cropping sequence. Faba bean (Vicia faba — winter) fixed 135–244 kg N ha⁻¹ and soybean (Glycine max — summer) fixed 453–488 kg N ha⁻¹ and contributed up to 155 and 280 kg fixed N ha⁻¹, respectively, to the soil after seed harvest. Green-manured field pea (Pisum sativum — winter) and lablab (Lablab purpureus — summer) fixed 123–209 and 181–240 kg N ha⁻¹, respectively, before the crops were slashed and incorporated into the topsoil.In a separate experiment, the loss of N from ¹⁵N-labelled legume residues during the fallow between legume cropping and cotton sowing (5–6 months following summer crops and 9 months after winter crops) was between 9 and 40% of ¹⁵N added; in comparison, the loss of ¹⁵N fertilizer (urea) applied to the non-legume plots averaged 85% of ¹⁵N added. Little legume-derived ¹⁵N was lost from the system during the growth of the subsequent cotton crop.The improved N fertility of the legume-based systems was demonstrated by enhanced N uptake and lint yield of cotton. The economic optimum N fertilizer application rate was determined from the fitted N response curve observed following the application of N fertilizer at rates between 0 and 200 kg N ha⁻¹ (as anhydrous ammonia). Averaged over the three experiments, cotton following non-legume rotation crops required the application of 179 kg N ha⁻¹, whilst following the grain- and green-manured legume systems required only 90 and 52 kg N ha⁻¹, respectively.In addition to improvements in N availability, soil strength was generally lower following most legume crops than non-legume rotation crops. Penetrometer resistance during the growth of the subsequent cotton crop increased in the order faba bean, lablab, field pea, wheat, cotton, and soybean. It is speculated that reduced soil strength contributed to improvement in lint yields of the following cotton crops by facilitating the development of better root systems.  相似文献   

Effect of nitrogen supply on crop conductance,water- and radiation-use efficiency of wheat     

《Field Crops Research》2001,69(3):259-266

Water-use efficiency (WUE_DM) is directly related to radiation-use efficiency (RUE) and inversely related to crop conductance (g_c). We propose that reduced WUE_DM caused by shortage of nitrogen results from a reduction in RUE proportionally greater than the fall in conductance. This hypothesis was tested in irrigated wheat crops grown with contrasting nitrogen supply; treatments were 0, 80 and 120 kg N ha⁻¹ in 1998 and 0, 80, 120 and 160 kg N ha⁻¹ in 1999. We measured shoot dry matter, yield, intercepted solar radiation and soil water balance components. From these measurements, we derived actual evapotranspiration (ET), soil evaporation and transpiration, WUE_DM (slope of the regression between dry matter and ET), WUE_Y (ratio between grain yield and ET), RUE (slope of the regression between dry matter and intercepted radiation), and g_c (slope of the regression between transpiration and intercepted radiation). Yield increased from 2.3 in unfertilised to an average 4.7 t ha⁻¹ in fertilised crops, seasonal ET from 311 to 387 mm, WUE_DM from 23 to 37 kg ha⁻¹ mm⁻¹, WUE_Y from 7.6 to 12.4 kg ha⁻¹ mm⁻¹, RUE from 0.85 to 1.07 g MJ⁻¹, while the fraction of ET accounted for soil evaporation decreased from 0.20 to 0.11. In agreement with our hypothesis, RUE accounted for 60% of the variation in WUE_DM, whereas crop conductance was largely unaffected by nitrogen supply. A greater fraction of evapotranspiration lost as soil evaporation also contributed to the lower WUE_DM of unfertilised crops.  相似文献   

Effect of N fertilizer top-dressing at various reproductive stages on growth,N2 fixation and yield of three soybean (Glycine max (L.) Merr.) genotypes     

《Field Crops Research》2003,80(2):147-155

Soybean (Glycine max (L.) Merr.) is one of the most important food and cash crops in China and a key protein source for the farmers in northern China. Previous experiments in both the field and greenhouse have shown that N₂ fixation alone cannot meet the N requirement for maximizing soybean yield, and that N top-dressing at the flowering stage was more efficient than N top-dressing at the vegetative stages. However, the effect of N fertilizer application at other reproductive stages of soybean is unknown. Thus, a field experiment was conducted to study the effects of N applications at various reproductive stages on growth, N₂ fixation and yield of three soybean genotypes. The results showed that starter N at 25 kg ha⁻¹ resulted in minimum yield, total N accumulation and total amount of N₂ fixed in all three genotypes. N top-dressing at 50 kg ha⁻¹ at either the V2 or R1 stages, significantly increased N accumulation, yield and total amount of N₂ fixed in all three genotypes. However, N top-dressing at the same rate at either the R3 or R5 stage did not show this positive effect in any of the three genotypes. Thus, the best timing for N top-dressing during reproduction is at the flowering stage, which increased seed yield by 21% for Wuyin 9, 27% for You 91-19, and 26% for Jufeng, respectively, compared to the treatment without N top-dressing.  相似文献   

The effect of late-season urea spraying on grain yield and quality of winter wheat cultivars under low and high basal nitrogen fertilization     

《Field Crops Research》2006,96(1):125-132

The late-season foliar application of urea may increase yield and grain quality of wheat (Triticum aestivum L.). Limited information is available regarding the effect of late urea spraying on the performance of wheat cultivars under various basal N fertilization rates. Field experiments were conducted during 2000 through 2002 to evaluate the responses of six winter wheat cultivars to foliar urea (30 kg N ha⁻¹) treatment around flowering at low (67 kg N ha⁻¹) and high (194 kg N ha⁻¹) basal N fertilization rates. Following urea spraying at low N rate, all cultivars increased grain yields to a similar extent (by an average of 7.8% or 509 kg ha⁻¹) primarily due to an increase in the 1000-kernel weight. No yield response to the late-season urea treatment occurred at high basal N rate where grain yields averaged 24.9% (1680 kg ha⁻¹) higher than those at low N rate. In contrast, late foliar urea application similarly improved grain quality at both low and high N rates by an average of 5 g kg⁻¹ (4.5%) for protein content, 3.2 cm³ (11.9%) for Zeleny sedimentation, and 20 g kg⁻¹ (8.6%) for wet gluten. These quality increments were consistent in all growing seasons regardless of significant variations in grain yields and protein concentrations across years. However, most cultivars failed to achieve breadmaking standards at low N rate as quality increments associated with the urea treatment were relatively small when compared to those achieved by high basal N rate. Late urea spraying had no effect on the falling number, whereas some cultivars showed small, but significant reduction in the gluten index at both N rates. Cultivars improved the hectolitre weight with the late-season urea treatment only at low N rate. Significant cultivar × urea interactions existed for most quality traits, which were due to the cultivar differences in the magnitude of responses. Thus, late-season urea spraying consistently produced larger yields at low basal N rate, and resulted in cultivar-dependent increases in protein content, Zeleny sedimentation, and wet gluten at both low and high N rates.  相似文献   

On-farm soil N supply and N nutrition in the rice–wheat system of Nepal and Bangladesh     

《Field Crops Research》1999,64(3):273-286

On-farm research to evaluate the productivity and nitrogen (N) nutrition of a rice (Oryza sativa L.)–wheat (Triticum aestivum L.) cropping system was conducted with 21 farmers in the piedmont of Nepal and with 21 farmers in northwest Bangladesh. In Nepal, two levels of N-fertilizer (0–22–42 and 100–22–42 kg N–P–K ha⁻¹) and farmers’ nutrient management practices were tested in the rice season, and three levels of N (0–22–42, 70–22–42, and 100–22–42) and farmers’ practices were evaluated in the wheat season. The treatments in Bangladesh included a researchers managed minus-N plot (0–22–42) and the farmers’ practices. Rice and wheat yields were higher in all treatments than the 0–22–42 control plots, with the exception of rice with the farmers’ practices at one location in Bangladesh. The researchers’ treatment of 100–22–42 in Nepal resulted in larger yields of both rice and wheat than the farmers’ practices, indicating that farmers’ rates of N-fertilizer (mean 49 kg N ha⁻¹) were too low. Delaying wheat seeding reduced yields in the fertilized plots in both countries, especially as N-fertilizer dose increased. Soil N-supplying capacities (SNSC), measured as total N accumulation from the zero-N plots (0–22–42), and grain yields without N additions were greater for rice than for wheat in both Nepal and Bangladesh. Higher SNSC in rice was probably due to greater mineralization of soil organic N in the warm, moist conditions of the monsoon season than in the cooler, drier wheat season. However, SNSC was not correlated with total soil N, two soil N availability tests (hot KCl-extractable NH₄⁺ or 7-day anaerobic incubation), exchangeable NH₄⁺ or NO₃⁻. Wheat in Nepal had greater N-recovery efficiency, agronomic efficiency of N, and physiological efficiency of N than rice. Nitrogen internal-use efficiency of rice for all treatments in both countries was within published ranges of maximum sufficiency and maximum dilution. In wheat, the relationship between grain yield and N accumulation was linear indicating that mobilization of plant N to the grain was less affected by biotic and abiotic stresses than in rice.  相似文献   

The efficiency of nitrogen fertiliser for rice in Bangladeshi farmers’ fields     

《Field Crops Research》2005,93(1):94-107

Bangladesh is currently self sufficient in rice (Oryza sativa L.), which accounts for approximately 80% of the total cropped area, and 70% of the cost of crop production. However, farmers are increasingly concerned about the perceived decline in productivity, expressed as the return on fertiliser inputs. Agronomic efficiency is a measure of the increase in grain yield achieved per unit of fertiliser input that can provide a way to quantify the observation of farmers. This study indicates that the yields achieved where only P and K fertiliser were applied ranged from 3–5 t ha⁻¹, indicating good soil fertility, particular in terms of soil N supply (37–112 kg N ha⁻¹). However, at recommended rates and at rates used by farmers, the yield response to application of fertiliser N was low. Data shows that grain yields were significantly correlated in both years (R² = 0.77 and R² = 0.67) with plant uptake in nitrogen. The internal nitrogen use efficiency seems to confirm that sink formation was limited by factors other than nitrogen. Low agronomic efficiency (5–19 kg grain kg⁻¹ N) was caused by poor internal efficiency (45–73 kg grain kg⁻¹ N), rather than low supply of soil N or loss of fertiliser N. Thus, often the applications of large amounts of N fertiliser (39–175 kg N ha⁻¹) by farmers to increase yields of high yielding variety Boro rice were not justified agronomically and ecologically. A rate of 39 kg N ha⁻¹ is very low, hardly an environmental threat. No one single factor could be identified to explain the low internal efficiency. Therefore, it is concluded that the data presented tend to confirm the indication that yields are limited by a factor other than nitrogen, which could be crop establishment, plant density, water or pest management, micro-nutrients deficiency, poor seed and transplanted seedling quality, varieties and low radiation.  相似文献   

Effect of irrigation and nitrogen fertilization on biomass yield and efficiency of energy use in crop production of Miscanthus     

《Field Crops Research》1999,63(1):3-11

The perennial C₄ grass Miscanthus has been proposed as a biomass energy crop in Europe. Effects of crop age, irrigation and nitrogen fertilization on biomass and energy yields and N content of Miscanthus were investigated and the energy costs of production determined. After an establishment period of 1 year, cultivation of Miscanthus resulted in a dry matter production of over 37 t ha⁻¹ year⁻¹ over a period of 4 years. Irrigation and nitrogen level greatly affected Miscanthus biomass yield. In absence of N fertilization, irrigation did not modify biomass yield and the effect of irrigation increased with the increase in N level. The average N response ranged from 37 to 50 kg biomass kg⁻¹ N applied. Because the calorific value of Miscanthus biomass (16.5 MJ kg⁻¹) was not affected by irrigation and N fertilization, energy production depended exclusively on biomass yield. Maximum energy yield was 564 GJ ha⁻¹ year⁻¹. Without N supply and irrigation, energy yield was 291 GJ h⁻¹. Net energy yield, calculated as the difference between energy output and input, but without inclusion of drying costs, was 543 GJ ha⁻¹ with N fertilization and irrigation and 284 GJ ha⁻¹ without; the ratios of energy output to input in crop production were 22 and 47, respectively.  相似文献   

Residual effect of poultry litter applied to cotton in conservation tillage systems on succeeding rye and corn     

《Field Crops Research》2001,71(3):159-171

The burgeoning poultry industry in the southeastern US is presenting a major environmental problem of safe disposal of poultry litter (PL). In a comprehensive study, we explored ways of PL use in conservation tillage-based cotton (Gossypium hirsutum L.) production systems on a Decatur silt loam soil in north Alabama, from 1996 to 1999. The study reported here-in presents the residual effects of PL applied to cotton in mulch-till (MT) and no-till (NT) conservation tillage systems in 1997 and 1998 cropping seasons on N uptake, growth, and yield of rye (Secale cereale, L.) cover crop and rotational corn (Zea mays L.) in 1999. Rye was grown without additional N, whereas corn was grown at three inorganic N levels (0, 100, and 200 kg N ha⁻¹). Poultry litter was applied to cotton in 1997 and 1998 at 0, 100, and 200 kg N ha⁻¹. Residual N from PL applied to cotton in 1997 and 1998 produced up to 2.0 and 17.3 Mg ha⁻¹, respectively, of rye cover crop and corn biomass (includes 7.1 Mg ha⁻¹ of corn grain yield) without additional fertilizer. Therefore, in addition to supplying crop residues which reduce soil erosion, increase soil organic matter, and conserve soil moisture, the rye cover crop was able to scavenge residual N left by the cotton crop, which would otherwise, be at risk of being leached and pollute groundwater resources. Poultry litter applied to cotton also increased corn grain quality as shown by up to 100% increase in grain N content compared to the 0N treatment. Using PL with a slower rate of N release compared to inorganic fertilizer to meet some of the N requirements of corn, will not only reduce N fertilizer costs for corn, but will also reduce the risk of nitrate N leaching into groundwater. The maximum amount of crop residues added to the cotton based cropping system by residual N from PL and inorganic N was 21.3 Mg ha⁻¹. This will lead to an increase in soil organic carbon and soil structure in the long term and a reduction in soil erosion, thereby further improving soil productivity, while at the same time, protecting the environment from nitrate pollution and soil degradation. Our study demonstrates that cotton under conservation tillage system in combination with rye cover crop and rotational corn cropping could use large quantities of PL thereby avoiding serious potential environmental hazards.  相似文献   

Nutrient and assimilate partitioning in two tropical maize cultivars in relation to their tolerance to soil acidity     

《Field Crops Research》2006,95(2-3):234-249

The use of Al-tolerant and P-efficient maize cultivars is an important component of a successful production system on tropical acid soils with limited lime and P inputs. Grain yield and secondary plant traits, including root and aboveground biomass, nutrient content and leaf development, were evaluated from 1996 to 2002 in field experiments on an Oxisol in order to identify maize characteristics useful in genetic improvement. Here we present the results of the 2002 trial and compare them with previous results. The aim of this experiment was to assess the effect of assimilate and nutrient partitioning on the growth and grain yield of two tropical cultivars having different Al tolerance (CMS36, tolerant, Spectral, moderately tolerant). The soil had an Al saturation of 36% in topsoil (pH 4.5) and >45% below 0.3 m depth (pH 4.2). Measurements made from emergence to grain filling included: root, stem and leaf biomass, P and N content, leaf area index (LAI), radiation use efficiency (RUE), soil available N and root profiles at anthesis. The experiments consisted of two P treatments, zero applied or 45 kg P ha⁻¹ (−P and +P). All the treatments received N and K fertilizers. In −P, root biomass and LAI at anthesis were twice as great in CMS36 as in Spectral. In +P the differences between cultivars were negligible. Roots were deeper in CMS36 due to its higher Al tolerance. Total biomass and grain yield were not strongly related to root biomass and LAI. Other factors such as the leaf biomass and the amount of nutrients per unit leaf area were highly correlated with RUE and biomass. In −P, Spectral had the same total biomass but a higher grain yield than CMS36 (2.1 Mg ha⁻¹ versus 1.5 Mg ha⁻¹). This was due to a higher leaf P content (+40%), a greater RUE (+74%), and a lower number of sterile plants. In +P, CMS36 had higher total biomass and grain yield (4.1 Mg ha⁻¹ versus 3.1 Mg ha⁻¹). This was due to its higher leaf P (+25%) and leaf N (+43%) contents, and an increased RUE (+130%) that were associated with higher P and N uptake. Our results indicated that although root tolerance to Al toxicity is necessary for good crop performance on acid soils, assimilate and nutrient partitioning in the aboveground organs play a major role in plant adaptation and may partially compensate for a lower root tolerance.  相似文献   

Water balance and rice growth responses to direct seeding,deep tillage,and landscape placement: Findings from a valley terrace in Nepal     

《Field Crops Research》2006,95(2-3):367-382

For maximizing water retention and attaining high yields, transplanting into puddled soil (TPR) is often considered the optimal method of rice (Orzya sativa L.) establishment. Alternative management techniques like direct seeding (DSR) and deep tillage have been proposed as mechanisms to improve soil physical properties for subsequent dry-season crops, but the risks to rice are uncertain. In this full factorial study on a valley terrace in Nepal, the influence of tillage (shallow—T₁, deep chisel—T₂, deep chisel + moldboard plough—T₃) and establishment practice (TPR, DSR) on the field water balance and rice performance were evaluated in two adjacent landscape settings (terrace edge “upland”, central terrace “lowland”). Although deep tillage had only modest influences on seepage and percolation (SP) rates in both years (Y₁, Y₂), landscape placement and establishment practice had significant implications for the water balance (e.g. Y₂ SP cm day⁻¹: TPR-lowland = 1.6, DSR-lowland = 2.3, TPR-upland = 4.1, DSR-upland = 6.1). During low rainfall periods, however, soil water potential and drought vulnerability were governed solely by landscape placement. Despite water balance differences, there was little evidence that rice rooting behavior was substantially modified by landscape or establishment method. Weed biomass was higher in DSR, but was uncorrelated with water balance and productivity trends. In Y₁, lower SP rates and more days with continuous flooding were positively associated with rice productivity. DSR yields were significantly lower than TPR in both landscape positions, with the lowland outperforming the upland (Y₁ mt ha⁻¹: TPR-lowland = 6.4, DSR-lowland = 5.2, TPR-upland = 5.7, DSR-upland = 4.7). To determine if N dynamics were contributing to productivity differences, fertilizer nitrogen was increased from 120 to 150 kg N ha⁻¹ in Y₂. Results suggest that DSR performance is comparable – and landscape less important – if nitrogen is non-limiting (Y₂ mt ha⁻¹: TPR-lowland = 6.9, DSR-lowland = 6.5, TPR-upland = 7.0, DSR-upland = 6.5); no aspect of the field water balance was associated with yield variability in Y₂. For direct seeding in N-deficient farming systems, landscape criteria may prove useful for minimizing production risks by identifying field areas with lower SP rates.  相似文献   

Pig slurry applications to alfalfa: Productivity,solar radiation utilization,N and P removal     

《Field Crops Research》2006,95(2-3):135-155

A field study was carried out over 4 years at one site in the Low Po Valley, Northern Italy, to examine the effect of various levels of pig slurry applications on alfalfa (Medicago sativa L.) productivity, solar radiation utilization, and nutrient removal. Treatments consisted of three liquid pig manure rates, estimated to provide in total 300, 450 and 600 kg N ha⁻¹ year⁻¹ (PS300, PS450, PS600, respectively), and one unfertilized control (named as Control). Treatments were applied on the second and third year of crop stand (1994 and 1995), whilst during the subsequent fourth and fifth years of crop stand (1996 and 1997) the residual effects of previous treatments were investigated. Regardless of crop age and year-to-year variability, pig slurry tended to increase annual forage production during the 2 years of fertilization and the subsequent biennium of stand duration. Overall, the forage dry matter production, accumulated over four growing seasons and 17 cuts, was 39 000 kg ha⁻¹ for the Control, 44 500 kg ha⁻¹ (+14%) for PS300, to 49 800 kg ha⁻¹ (+28%) for PS450 and 45 800 kg ha⁻¹ (+17%) for PS600. Nitrogen concentration in shoot dry matter was not influenced by the treatment applied. P concentration, on the other hand, was substantially increased by all three rates of pig slurry application, with an evident residual effect observed during the last 2 years of crop stand. However, the evident increase of P availability, assured by pig slurry fertilization, resulted in most of cases in luxury consumption of P by the crop plant. A strong linear relationship was found between cumulative forage dry matter and accumulated incident global solar radiation. Pig slurry fertilization increased significantly the slope of the regressions with respect to the Control. Since enhanced N and P availability may reduce the carbon costs for sustaining root nodules and symbiotic organisms, it seems likely that the crop plant must gain advantage in terms of dry matter produced per unit of radiation intercepted. However, further research is needed to clarify whether the effect of manure is attributable to improved alfalfa efficiency in converting intercepted solar energy into forage dry matter, to enhanced canopy cover thus higher radiation capture per unit of soil area, or to a combination of both mechanisms.  相似文献