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1.
Efficient use of external inputs and water conservation are a prerequisite of sustainable agricultural productivity in semiarid West Africa. A field experiment was carried out during 3 years (2000–2002) at Saria in semiarid Burkina Faso (800 mm of annual rainfall, PET of 2000 mm per year) to assess the effects of stone rows or grass strips of Andropogon gayanus Kunth cv. Bisquamulatus (Hochst. Hack.) as soil and water conservation (SWC) measures, the sole application of an organic (compost-N) or mineral (urea-N) nitrogen and the combined use of SWC and compost-N or urea-N on N flows and balances. The trial was conducted on a Ferric Lixisol with 1.5% slope and comprised nine treatments in two replications. The SWC measures were put along contours lines. During the three consecutive years, all treatments induced negative annual N balances (−75 to −24 kg N ha−1). The main factors explaining these negative balances were N exports by sorghum biomass and soil erosion-induced N losses. Large amounts of N (7 kg N ha−1 per year in 2000 and 44 kg N ha−1 per year in 2002) were lost in the control treatment through runoff and eroded sediments, which corresponds respectively to about 10 and 43% of the total outflow of N. Sole stone rows and grass strips reduced erosion N losses to 8 and 12%, respectively, of the total annual loss. The combined application of SWC measures and nutrients inputs reduced erosion N losses to only 2–7% of the annual N loss. The application of urea-N or compost-N led to the lowest soil N mining over the 3 years, whereas the highest N mining was observed in plots without added N. We conclude that N mining in poor fertile soils of West Africa can be mitigated through an integration of local water and nutrient management practices.  相似文献   

2.
《Field Crops Research》2004,90(2-3):203-212
Previous research indicated that prolific (multi-ear) maize (Zea mays L.) hybrids might perform better than nonprolific (single-ear) hybrids under lower-yielding environments. Field experiments were conducted during 1996–1999 to evaluate the agronomic responses of 10 maize hybrids differing in ear prolificacy under reduced-input and high-input cropping systems. Hybrids were of similar maturity (FAO 400) and divided into two prolificacy groups (prolific versus nonprolific), each consisting of five hybrids. The reduced-input system consisted of plowing at 20–22 cm; fertilization at 105, 104, and 104 kg ha−1 N, P2O5, and K2O; 37–38 000 plants ha−1; and low input of herbicide. The high-input system involved plowing at 30–32 cm; fertilization at 213, 130, and 130 kg ha−1 N, P2O5, and K2O; 60–65 000 plants ha−1; and high input of herbicides. Grain yields significantly decreased under reduced-input compared to high-input cropping system by an average of 26.1%. Significant cropping system×prolificacy group interactions were found for most yield components but not for grain yields. This indicated that both prolificacy groups exhibited a similar yield decrease under the reduced-input system even though prolific hybrids had 1.33 ears per plant compared to only 1.01 ears per plant of nonprolific types. All prolific hybrids responded similarly to various cropping input levels principally by means of changes in kernels per plant, whereas some nonprolific hybrids had greater response through 1000-kernel weight then kernels per plant. Prolific hybrids tended to achieve higher grain yields which averaged 10 414 kg ha−1 compared to 9383 kg ha−1 for nonprolific types partly due to less barren plants per hectare and primarily because of a higher grain weight per plant. Larger grain weights per plant of prolific hybrids were primary due to more kernels per plant in the reduced-input system, and a combined effect of more kernels and heavier 1000-kernel weight per plant in the high-input system. Improved kernel number per plant for prolific hybrids was associated with kernels from secondary ears. Although prolific hybrids outyielded nonprolific types, our findings failed to indicate that the prolificacy trait per se had any important effect on hybrid performance when grown under reduced-input compared to high-input cropping system.  相似文献   

3.
A mixture of 1,3-dicloropropene 60.5% w/w and chloropicrin 33.3% w/w (Telone C35 EC) may be registered in Italy for soil drip fumigation. Five experiments on greenhouse tomatoes in Northern, Central and Southern Italy compared the effectiveness of this mixture in comparison with methyl bromide to find the optimum application rate in soils infested by Fusarium oxysporum f.sp. lycopersici, F. oxysporum f.sp. radicis lycopersici, Sclerotium rolfsii, Meloidogyne javanica and M. incognita. Its efficacy against F. oxysporum f.sp. radicis lycopersici and M. incognita was confirmed when applied to soils at 100, 200, 300 and 400 l ha−1 (132.4, 268.4, 402.6 and 536.8 kg ha−1) under gas-tight films with 15–45 mm of application water (900–1200 mg Telone C35 EC l−1). In sandy soils, with slight F. radicis lycopersici infections and with heavy nematode (M. incognita) attacks, the mixture, drip applied at 900 mg l−1 during late summer (fumigation: late summer; transplant: late-summer/autumn; last harvest: early spring), performed well up to 132.4 kg ha−1 (100 l ha−1). In sandy loam soils with slight F. radicis lycopersici infections and severe infections of F. lycopersici and galling nematodes (M. javanica), 268.4 kg ha−1 (200 l ha−1) of the mixture applied at 900 mg l−1 as a drip provided yields similar to those of methyl bromide treated plots both in spring and summer cycles. In sandy loam soils, the diseases (F. lycopersici, F. radicis lycopersici) were controlled at rates 268.4 kg ha−1 (containing 90 kg ha−1 of chloropicrin), but the mixture was ineffective against Sclerotium rolfsii occasionally observed in sandy loam soils. In both sandy and sandy loam soils, no significant relationships were found between the rates of mixture applied (132.4, 268.4, 402.6 and 536.8 kg ha−1) and the degree of nematode infestation.  相似文献   

4.
Rice (Oryza sativa L.) followed by chickpea (Cicer arietinum L.) or a fallow is one of the predominant cropping systems in the rainfed lowlands of India. Crop rotation experiments over 3 years (1996–1998) to quantify N supply and demand under rainfed lowland rice–chickpea and rice–fallow cropping systems on a loam Alfisol and a clay Vertisol in Raipur, India were conducted under direct-seeded rice culture. The rice growth, yield, development and N accumulation were affected most by N rates (0, 40, 80, 120 kg ha−1) followed by cropping system (rice–chickpea, rice–fallow) and soil types (Alfisol, Vertisol). The incorporation of chickpea in the cropping system helped in accumulating a greater amount of soil N than fallow. The rice yield, dry matter and N accumulated were significantly higher in rice–chickpea than rice–fallow systems on both soils and in all years. The lowest rice yields were recorded in 1997 due to unfavorable rainfall distribution. The total rainfall was the highest in this season, but most of it occurred during a short period at an early growth stage. The post-heading rains were lowest in this season and resulted in the lower rice yield as compared with that of 1996 and 1998. This indicates the significance of rainfall distribution in controlling yield in a rainfed environment. The rice yields were lower on Vertisol than Alfisol during periods of drought. The performance of chickpea was also better in Alfisol as compared with that in the Vertisol due to its better soil physical attributes. The residual effect of N applied to the preceding rice crop was non-significant on all yield, growth and N accumulation parameters of chickpea. The N balance computed from the top 70 cm soil layers indicated less N loss in the rice–chickpea system as compared with that in rice–fallow. The recovery efficiency at the highest N rate (120 kg N ha−1) was higher for the rice–chickpea (57–61%) than that of rice–fallow (49–53%) system. The improved N balance for rice–chickpea system from third year onwards was due to switch to dry seeding and improved soil N status. The inclusion of legume and the effective capture of biologically fixed N and soil N through direct-seeded rice system in rainfed lowlands may help in improving the rice yield of resource poor farmers.  相似文献   

5.
Responses of wheat grown on a heavy clay soil in the Goulburn-Murray Irrigation Region of south-eastern Australia to a factorial combination of three irrigation treatments and nitrogen and gypsum application were investigated.Irrigation treatments included a rainfed control (treatment RF) and irrigation on either a weekly (treatment Iw) or fortnightly (treatmnt IF) basis beginning in spring and maintained until physiological maturity. Nitrogen was applied at 0 and 150 kg N ha−1 (treatments N0 and N150, respectively) and gypsum at 0 and 5 t ha−1. Nitrogen and gypsum treatments were applied at sowing.

Yield increased from a mean of 4 t ha−1 treatment RF to 6.6 t ha−1 in treatments IF and IW, largely because of promotive effects of irrigation on kernel weight (increase from 31 mg to 42 mg kernel−1 and kernel spikelet−1 (1.4 as compared with 1.7). Seasonal conditions and the relative fertility of the site were sufficient to maximise spike number and spikelet spike−1. Nitrogen increased kernel spikelet−1 but effects on yield were not significant because of a decrease in kernel weight. Effects of gypsum on yield were not significant.

Water-use efficiency of both rainfed and irrigated treatments was ca. 1.25 g grain kg−1 H2O. However, transpirational water-use efficiency, calculated after allowing 110 mm water for soil evaporation, fell from 2 g kg−1 in treatment RF to 1.7 and 1.5 g kg−1 in treatments IF and IW, respectively. The decrease was ascribed, in part, to lodging and soil evaporative losses may have been in excess of 110 mm with more frequent irrigation. Effects of N on water use could not be distinguished, again because of the initial fertility of the site, which supported rapid growth and resulted in complete canopy closure.

Nitrogen and irrigation treatments had independent effects on the concentration of N in the grain (%NG) which increased by a mean of 0.6% with N treatment despite a decrease in N harvest index (HIN) from 0.77 to .70. Irrigation decreased %NG by approximately 0.5%. Approximately 90 kg pN ha−1 was found in the grain of treatments RFN0, IWN0, IwN0 and RFN150 and differences in %NG in these treatments attributed to a ‘dilution’ effect mediated by the increase in yield effected by irrigation. The grain accounted for approximately 115 kg N ha−1 in treatments IFN150 and IWN150, countering the inverse relationship between %Ng and yield despite the increase in HIN index caused by N application.  相似文献   


6.
M.A.K. Smith   《Crop Protection》2006,25(12):1221-1226
Field experiments and bioassay tests were carried out to evaluate the relative response of the crops, tossa jute (Corchorus olitorius L.) and okra [Abelmoschus esculentus (L.) Moench], and their associated weeds to pre-emergence application of pendimethalin at 0.33, 0.66, 0.99, 1.32 kg ai ha−1 and a pendimethalin+atrazine tank mixture at 1.32+2.05 kg ai ha−1. Bioassay tests were carried out using herbicide solutions of corresponding concentrations and herbicide-treated soil. Field application of pendimethalin at 0.66 kg ai ha−1 and the herbicide mixture in both crops effectively controlled most seedling weeds including Rottboellia cochinchinensis. Euphorbia heterophylla and Calopogonium mucunoides, which persisted from 2 weeks after treatment (WAT) were not controlled. Herbicide application during crop establishment markedly inhibited the growth of both seedling weeds and crops. The mixture caused the highest weed and crop injury. Pendimethalin at 0.33 kg ai ha−1 had minimal effect on these crops. Weed growth, weed tolerance of herbicide treatment and crop seedling injury were higher in tossa jute than that in okra, under the conditions of this study. The use of low pendimethalin doses in an integrated weed management system will ensure effective control of seedling weeds, and prevent crop injury and residue accumulation in edible plant produce.  相似文献   

7.
Subsoil constraints are major limiting factors in crop production in many soils of southern Australia. A field study examined effects of deep incorporation of organic and inorganic amendments in 30–40 cm on soil properties, plant growth and grain yield of wheat (Triticum aestivum var. Ambrook) on a Sodosol with dense sodic subsoil with or without lucerne history in a high rainfall region (long-term average annual rainfall 576 mm) of Victoria. Amendments were applied at a rate of 10–20 t ha−1. Deep ripping alone and deep ripping with gypsum did not significantly affect grain yields. In comparison, application of organic materials doubled biomass production and increased grain yield by 1.7 times. Organic amendment-treated plots produced 60% more grains per area than the untreated control. The crop extracted over 50 mm extra water from below 40 cm soil in organic amendment-treated plots than the untreated control. Nitrogen uptake was almost doubled (403 kg ha−1) in the organic amendment-treated plots than the untreated control (165 kg ha−1). The improved yield with amendments was related to an increase in plant available water in the hostile subsoil, and prolonged greenness of leaves and supply of nitrogen and other nutrients.  相似文献   

8.
Over time, the relative effect of elevated [CO2] on the photosynthesis and dry matter (DM) production of rice crops is likely to be changed with increasing duration of CO2 exposure, but the resultant [CO2] effects on rice N concentration, uptake, efficiency and allocation remain unclear, especially under different soil N availability. Therefore, we conducted a free-air CO2 enrichment (FACE) experiment at Wuxi, Jiangsu, China, in 2001–2003. A japonica cultivar with large panicle was grown at ambient or elevated (ca. 200 μmol mol−1 above ambient) [CO2] under three levels of N: low (LN, 15 g N m2), medium (MN, 25 g N m2) and high N (HN, 35 g N m2 (2002, 2003)). The MN level was similar to that recommended to local farmers. Averaged across all N levels and years, shoot N concentration (dry base) was lower under FACE by 1.8%, 6.1%, 12.2%, 14.3%, 12.1%, and 6.9% at early-tillering, mid-tillering, panicle initiation (PI), booting, heading and grain maturity, respectively. Shoot N uptake under FACE was enhanced by 46%, 38%, 6% and 16% on average during the growth periods from transplanting to early-tillering (period 1), early-tillering to mid-tillering (period 2), mid-tillering to PI (period 3) and heading to grain maturity (period 5), respectively, but slightly decreased by 2% in the period from PI to heading (period 4). Seasonal changes in crop response to FACE in ratio of shoot N uptake during a given growth period to that over the whole season followed a similar pattern to that of shoot N uptake, with average responses of 33%, 26%, −3%, −11% and 10% in periods 1–5 of the growth period, respectively. As a result, FACE increased final aboveground N uptake by 9% at maturity. FACE greatly reduced the ratio of leaf to shoot N content over the season, while allocation of N to stems and spikes showed an opposite trend. FACE treatment resulted in the significant increase in N use efficiency for biomass (NUEp) over the season except at early-tillering and in N use efficiency for grain yield (NUEg) at grain maturity. These results indicate that, in order to maximize grain output in a future high [CO2] environment, the recommended rates, proportion and timing across the season of N application should be altered, in order to take full advantage of strong N uptake capacity during the early growth period and facilitate N uptake after that.  相似文献   

9.
A. E. Abdullahi   《Crop Protection》2002,21(10):1093-1100
Field experiments were conducted during two cropping seasons at two sites in Botswana to determine the efficacy of combining glyphosate and tillage in controlling C. dactylon. Treatments consisted of no-tillage, single and double ploughing during winter and spring plus the application of glyphosate at 0, 1.08, and 2.16 kg ha−1 3–4 weeks after the last ploughing. Visual assessment indicated higher levels of grass control from combining glyphosate and tillage than when these elements were applied separately. However, biomass data indicated that either double ploughing or glyphosate application controlled C. dactylon. A single ploughing followed by glyphosate at 2.16 kg ha−1 after a regrowth of C. dactylon may provide an effective and affordable control method to small-scale farmers.  相似文献   

10.
Efficiencies in uptake and use of N by maize cultivars have been widely studied, but little has been done on this subject in West Africa. Six single-cross hybrids, three double-cross hybrids and a synthetic line were grown at different N levels (0–210 kg N ha−1) in three ecological zones of West Africa. The maize cultivars differed widely in grain yield and N-accumulation parameters. Most cultivars absorbed similar amounts of N ranging from 2.04 g plant−1 to 2.60 g plant−1, but produced different grain yields, with those that accumulated more N after silking tending to have higher grain yield. Grain yields in the forest zone were lower than those in two Savanna regions. Differences were also observed for N-uptake (total N-uptake per unit N supplied to the soil), N-utilization (grain produced per unit N absorbed from the soil) and N-use efficiency (NUE) (grain produced per unit N supplied to the soil). Cultivars varied in their response to change in available soil N. The hybrids were more efficient in N-use and its component traits than the synthetic cultivar. Hybrid 1368 × KU1414-SR yielded the most grain as well as exhibiting superior traits for N-uptake and N-use efficiency.  相似文献   

11.
Globe artichoke (Cynara scolymus L.) and cultivated cardoon (C. cardunculus L. var. altilis DC.) are horticulturally important crop plants. These species have potential as biomass and oilseed crops. We field tested, for 3 years, two artichoke and two cardoon cultivars and one wild cardoon (C. cardunculus L. var. sylvestris Lam.) population on the Sicilian plain of Catania (37°27′ N, 15°04′ E, 10 m a.s.l.). On a 3-year average, the dry aboveground biomass resulted about 31 t ha−1 in both cultivated cardoons, 18.8 t ha−1 in wild cardoon, 13.7 t ha−1 in globe artichoke ‘3/10 V.S.’ and 9.9 t ha−1 in globe artichoke ‘374’ F1. The caloric values of aboveground biomass (except for seeds), which was not significantly different among genotypes, ranged between 16 005 and 17 028 KJ kg−1 of dry matter. The cultivated cardoon ‘Gigante di Lucca’ had the greatest grain yield (on 3-year average, 2.6 t ha−1), whereas the two globe artichokes had the lowest yield (on 3-year average, 0.5 t ha−1). Regardless of genotypes and years, the grains contain 20.1% crude protein, 24.4% oil, 18.5% crude fiber and 4.1% ash (dry weight basis). The grains of globe artichokes showed the highest crude protein content (21.6%), whereas those of cardoons the highest oil content (25.2%).  相似文献   

12.
Much of the rapidly growing demand for rice in West Africa will be met from increased production in irrigated lowlands, which cover about 12% of the regional rice-growing area. A large potential for expansion of irrigated areas exists particularly in the inland valleys of the humid forest zone. Current production is characterized by large variability in productivity, management practices and production constraints. Quantifying the variability in rice yield and identifying the determining factors are prerequisites to the development of site-specific recommendations and to improved targeting of technologies. Diagnostic on-farm trials were conducted on 64 irrigated lowland fields in the humid forest zone of southern Côte d'Ivoire, in 1995–1996. This was a part of the regional gradient study of irrigated systems from the desert margin to the humid forest zone. Cropping calendars, field operations and input use were monitored. Weed biomass, rice N uptake, and grain yield were determined in farmers' fields as well as in super-imposed, researcher-managed subplots (clean weeding, no N control, and mineral fertilizer N application). Rice yield potential was simulated by using the Oryza-S crop growth model. Yield losses were attributed to management factors based on performance of rice in researcher-managed subplots (management-related yield gap) and by multiple regression with management options. Grain yields varied between 0.2 and 7.3 Mg ha−1 with mean yields of 3.2 in partially and 4.2 Mg ha−1 in fully irrigated systems, 44% and 57% of the potential yield of 7.3 Mg ha−1, respectively. Age of seedlings at transplanting, timeliness of operations and application of P fertilizer were correlated to yield and explained 60% of the observed variability. Grain yield was correlated with N uptake (r2 = 0.93***) but not with N application rate. Split application of mineral fertilizer N was associated with a 0.48 Mg ha−1 yield increase (p = 0.002), regardless of the quantity applied. Additional weeding increased yield only in systems with imperfect irrigation. Weed biomass was reduced with improved water control and it increased with age of seedlings at transplanting, and was higher in direct-seeded than in transplanted rice. Echinochloa spp. were the most common weeds in fully irrigated systems and Panicum laxum was more common in the imperfectly irrigated fields. While improved water management was associated with substantial rice yield increases (1.16 Mg ha−1), the timeliness of transplanting, weeding and N fertilization appears to be the key to increased rice yields in the forest zone of West Africa.  相似文献   

13.
In high productivity zones of Indo-Gangetic Plains in south Asia, the rice–wheat system is stressed due to production fatigue as evidenced by declining soil organic matter content, low efficiency of fertilizer use and diminishing rates of factor productivity. We, therefore, conducted field experiments at Modipuram, India, to conserve soil organic carbon, improve N and P use efficiency, and increase yields of rice–wheat system through inclusion of forage cowpea during the summer before cultivating the rice–wheat system. Cowpea forage harvested at 50 days removed greater amounts of N and P through aboveground biomass than those recycled through belowground roots and nodules. The NO3-N in soil profile below 45 cm depth after wheat harvest was greater under fallow during summer than under cowpea, suggesting that cowpea minimized NO3-N leaching beyond 45 cm depth. Similarly, in the treatments receiving both 120 kg N and 26 kg P ha−1, NO3-N in soil below 45 cm depth was lower compared to those receiving N or P alone. After three crop cycles, soil OC content in 0–15 and 15–30 cm depths was greater compared to initial OC in plots having cowpea. P applied at 26 kg ha−1 increased available P content over initial P content, and also over P content of soil under no P treatments. The available P content was, however, invariably low under summer cowpea plots as compared to that under no cowpea ones. With continuous rice–wheat cropping, the bulk density (BD) of soil increased over the initial BD at different profile-depths, more so at 30–45 cm depth in no cowpea plots, but inclusion of summer cowpea helped decreasing the BD in the surface (0–15 cm) and sub-surface (15–30 and 30–45 cm) soil layers. Summer cowpea grown on residual fertility after wheat harvest did not influence rice yield, but increased wheat grain yield (P<0.05 during the terminal year), when both the crops received fertilizer N and P at recommended rates. Skipping of N or P or both, however, resulted in consistently low yield of these crops under summer cowpea treatments than those under no cowpea treatments, although the differences were not necessarily significant every year. The use efficiency of applied N and P fertilizers in rice and wheat, measured as agronomic efficiency and apparent recovery, was increased with the use of fertilizer N and P at recommended rates, and also with inclusion of summer cowpea.  相似文献   

14.
The opportunity for site-specific management of crops depends on both the magnitude and spatial structure of yield variation. This study explored the applicability of Lorenz curves and Gini coefficients (G) to characterise the magnitude of the variation in grain yield. Maize crops were grown in farmers fields in a semi-arid region of central Argentina. Major sources of yield variation between and within paddocks included season, soil type and topography, rate of nitrogen fertiliser (nil to 132 kg N ha−1), and the interactions among these factors. Nitrogen treatments were applied in a complete block strip trial (strip size700 m×9.8 m) with three replicates. Data were collected with an AgLeader™ yield monitor, and GIS software was used to create 9.8 m×9.8 m grids over the observations. Average yield in 0.7–2.8 ha field sections ranged from 1.6 to 7.0 t ha−1. Gini coefficient ranged from 0.027 to 0.191 whereas its theoretical limits are 0 for a perfectly uniform population, and 1 for a theoretical population of infinite size where all units but one yield 0. Conditions conducive to high yield, e.g. adequate availability of nitrogen and water, reduced crop yield inequality, as quantified with G. The agronomic relevance of G was summarised in an inverse relationship with yield. Lorenz curves seemed particularly apt to present crop heterogeneity in terms of inequality, and to highlight the relative contribution of low- and high-yielding sections of the field to total paddock yield. Lorenz curves and Gini coefficients provide a potentially useful extension tool, a complement to yield maps and other statistical indices of yield variation, and further contact points between site-specific management, economics and ecology.  相似文献   

15.
The effect of nitrogen (N) supply and weeds on grain yield of spring barley was investigated from 1997 to 2004 in an organic farming crop rotation experiment in Denmark on three different soil types varying from coarse sand to sandy loam. Two experimental factors were included in the experiment in a factorial design: (1) catch crop (with and without), and (2) manure (with and without). The crop rotation included grass-clover as a green manure crop. Animal manure was applied as slurry in rates corresponding to 40% of the N demand of the cereal crops.

Application of 50 kg NH4-N ha−1 in manure (slurry) increased average barley grain DM yield by 1.0–1.3 Mg DM ha−1, whereas the use of catch crops (primarily perennial ryegrass) increased grain DM yield by 0.2–0.4 Mg DM ha−1 with the smallest effect on the loamy sand and sandy loam soils and the greatest effect on the coarse sandy soil. Model estimations showed that the average yield reduction from weeds varied from 0.2 to 0.4 Mg DM ha−1 depending on weed species and density. The yield effects of N supply were more predictable and less variable than the effects of weed infestation. The infestation level of leaf diseases was low and not a significant source of yield variation.

The apparent recovery efficiency of N in grains (N use efficiency, NUE) from NH4-N in applied manure varied from 29 to 38%. The NUE of above-ground N in catch crops sampled in November prior to the spring barley varied from 16 to 52% with the largest value on the coarse sandy soil and the smallest value on the sandy loam soil. A comparison of grain yield levels obtained at the different locations with changes in soil organic matter indicated a NUE of 21–26% for soil N mineralisation, which is smaller than that for the mineral N applied in manure. However, this estimate is uncertain and further studies are needed to quantify differences in NUE from various sources of N.

The proportion of perennial weeds in total biomass increased during the experiment, particularly in treatments without manure application. The results show that manure application is a key factor in maintaining good crop yields in arable organic farming on sandy soils, and in securing crops that are sufficiently competitive against perennial weeds.  相似文献   


16.
Efficient use of cattle-slurry to avoid nitrogen (N) leaching and other losses is important in designing intensive dairy systems to minimize pollution of air and water. The response in dry-matter (DM) yield of herbage and nitrate-leaching potential to different rates and timing of application of N as cattle slurry and/or mineral fertilizer in a double-cropping system producing maize ( Zea mays L.) silage and Italian ryegrass ( Lolium multiflorum Lam.) was investigated in north-west Portugal. Nine treatments with different rates and combinations of cattle slurry, and with or without mineral-N fertilizer, applied at sowing and as a top-dressing to both crops, were tested and measurements were made of DM yield of herbage, N concentration of herbage, uptake of N by herbage and amounts of residual soil nitrate-N to a depth of 1 m, in a 3-year experiment. Regression analysis showed that the application of 150 and 100 kg of available N ha−1 to maize and Italian ryegrass, respectively, resulted in 0·95 of maximum DM yields of herbage and 0·90 of maximum N uptake by herbage. Residual amounts of nitrate-N in soil after maize ranged from 48 to 278 kg N ha−1 with an exponential increase in response to the amount of N applied; there were higher values of nitrate-leaching potential when mineral-N fertilizer was applied. The results suggest that it is possible in highly productive maize/Italian ryegrass systems to obtain high DM yields of herbage for maize silage and Italian ryegrass herbage with minimal leaching losses by using slurry exclusively at annual rates of up to 250 kg available N ha−1 (equivalent to 480 kg total N ha−1) in three applications.  相似文献   

17.
The effects of applying nitrogen (30 or 40 kg N/ha) to wheat crops at and after anthesis, after 200 kg N/ha had already been applied to the soil during stem extension, were studied in field experiments comprising complete factorial combinations of different cultivars, fungicide applications and nitrogen treatments. Actual recoveries of late-season fertilizer nitrogen (LSFN), as indicated by 15N studies, interacted with cultivar and fungicide treatment, and depended on nitrogen source (urea applied as a solution to the foliage, or as ammonium nitrate applied to the soil) and year. These interactions, however, were not reflected in apparent fertilizer recoveries ((N in grain with LSFN − N in grain without LSFN)/N applied as LSFN), or in the crude protein concentration. Apparent fertilizer recovery was always lower than actual recoveries, and declined during grain filling. Fertilizer treatments with higher actual fertilizer recoveries were associated with lower net remobilisation of non-LSFN (net remobilised N = N in above ground crop at anthesis − N in non-grain, above ground crop at harvest). LSFN also increased mineral nitrogen in the soil at harvest even when applied as a solution to the foliage. These effects are discussed in relation to potential grain N demand.  相似文献   

18.
The expected reduction in the use of fertilizer nitrogen (N) on grassland in the Netherlands has led to renewed interest in white clover. Therefore, the performance of a newly sown perennial ryegrass/white clover sward on clay soil was assessed during 4 consecutive years. The experiment consisted of all combinations of two defoliation systems, i.e. one or two silage cuts per year (S1, S2), spring N application rate, i.e. 0 or 50 kg ha−1 year−1 (N0, N50), and the management system, i.e. rotational grazing and cutting, or cutting only (RGC, CO). The overall mean white clover cover was 30%. All treatments affected white clover cover, which was 8% higher with S2 than with S1, 6% higher with N0 than with N50 and 12% higher with CO than with RGC. The overall mean annual dry-matter (DM) yield (13·1 t ha−1 year−1) was significantly affected only by the management system: in two relatively wetter years, the annual DM yield was 1·19 t ha−1 higher with RGC than with CO, whereas there was no difference in two relatively drier years. Nitrogen application increased the DM yield in the first cut by 7·0 kg kg−1 N applied, but had no significant effect on the annual DM yield. Herbage quality was not affected by the experimental treatments. The average in vitro organic matter digestibility was 0.801, and the average crude protein content was 193 g kg−1 DM. With the expected reduction in the use of fertilizer N, perennial ryegrass/white clover swards should be seriously considered as an alternative option to perennial ryegrass swards on these clay soils.  相似文献   

19.
A 3 years field trial examined the effect of newly and previously applied lime on the growth and yield of two near-isogenic wheat genotypes differing only in aluminium (Al) tolerance (Triticum aestivum L. Al-sensitive line ES8 and Al-tolerant line ET8), and barley (Hordeum vulgare cv. Mundak) on an acid soil (pHCaCl2 4.6 in 0–10 cm and pH 4.1–4.3 in 10–40 cm) in the medium rainfall region of Western Australia. The trial consisted of four lime treatments: (i) no lime control; (ii) surface liming at 1.5 t ha−1 in 1999; (iii) surface liming at 2.5 t ha−1 in 1984; (iv) liming in 1984 and re-liming in 1999. Wheat crops were grown in 1999 and 2001, and barley was grown in 2000.

Liming in 1984 increased the pH in both topsoil and subsoil and decreased toxic Al in the subsoil. Liming in 1999 largely increased soil pH in the 0–10 cm in previously unlimed and limed plots, but only slightly increased the pH in 10–20 cm 2 years after application. In 1999, there was an overall 14% grain yield increase by growing ET8, mostly due to much better performance (41%) of ET8 over ES8 in the treatment with surface liming in 1999. In 2001, ET8 had yield 24% higher in the no lime control and 14% higher in the treatment with liming in 1999 compared with ES8. While both genotypes had similar root length density in the topsoil, root length density in acid subsoil was 22–160% higher for ET8 than for ES8. Wheat genotypes produced 23–24% higher yield due to the liming in 1984 compared to the no lime control. In 2000 season, shoot biomass of barley increased by 45–70% in the limed treatments compared with the no lime control. Liming at 2.5 t ha−1 in 1984 or liming at 1.5 t ha−1 in 1999 increased yield by 25%. Liming in 1984 and re-liming in 1999 increased the yield by over 50%. The results suggest that surface liming can ameliorate subsoil acidity as measured 15–17 years after application, and that growing an Al-tolerant crop in combination with surface liming provides a good strategy to combat subsoil acidity. The genotypic variation in response to liming appears to result from the difference in the sensitivity of root proliferation to low pH and high Al.  相似文献   


20.
The effect of nitrogen (N) fertilization on the dry‐matter (DM) yield and nutritional value of sorghum (Sorghum sp., cv. Jumbo) and black oat (Avena strigosa cv., IPR 61) was investigated in the context of forage and livestock production in southern Brazil. Sorghum was cultivated with 0, 37·5, 75, 150, 225, 300 and 375 kg N ha?1 during the summer crop seasons of 2010/11 and 2011/12. Black oat received 0, 40, 80, 120, 160, 200 and 240 kg N ha?1 in the winter of 2011. According to the adjusted polynomial regression, sorghum DM yield increased in response to N up to 288 (12·9 t ha?1) and 264 kg ha?1 (5·6 t ha?1) in 2010/11 and 2011/12 respectively. Crude protein (CP) content of sorghum was highest at 349 and 328 kg N ha?1, but in vitro dry‐matter digestibility (IVDMD) was highest at 212–207 kg N ha?1 in 2010/11 and 2011/12 respectively. Sorghum neutral detergent fibre (NDF) and acid detergent fibre (ADF) were not affected by N fertilization. In black oat, the maximum DM yield (6·0 t ha?1) was obtained with 187 kg N ha?1; the IVDMD, NDF and ADF were not affected by N fertilization, but the CP content increased up to 220 kg N ha?1. It is concluded that these forage species can improve the year‐to‐year amount and quality of forage produced but high rates of N fertilizer are required to achieve high yields. Fertilizer N rates of 210–280 kg N ha?1 in sorghum and 180 kg N ha?1 in black oat in the crop rotation provide the greatest responses in DM yield consistent with good nutritional quality for livestock production.  相似文献   

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