Nitrogen dynamics and crop growth on an Alfisol and a Vertisol under a direct-seeded rainfed lowland rice-based system     

S. K. Patil  U. Singh  V. P. Singh  V. N. Mishra  R. O. Das  J. Henao 《Field Crops Research》2001,70(3):185-199

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   

Application of an emulsifiable mixture of 1,3-dichloropropene and chloropicrin against root knot nematodes and soilborne fungi for greenhouse tomatoes in Italy   总被引：6，自引：0，他引：6  

A. Minuto  M.L. Gullino  F. Lamberti  T. D&#x;Addabbo  E. Tescari  H. Ajwa  A. Garibaldi 《Crop Protection》2006,25(12):1244-1252

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   

Amelioration of dense sodic subsoil using organic amendments increases wheat yield more than using gypsum in a high rainfall zone of southern Australia     

J.S. Gill  P.W.G. Sale  C. Tang   《Field Crops Research》2008,107(3):265-275

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   

Performance of prolific and nonprolific maize hybrids under reduced-input and high-input cropping systems     

《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   

Nitrogen flows and balances as affected by water and nutrient management in a sorghum cropping system of semiarid Burkina Faso   总被引：3，自引：0，他引：3  

Robert Zougmor  Abdoulaye Mando  Leo Stroosnijder  Serge Guillobez 《Field Crops Research》2004,90(2-3):235-244

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   

On-farm measurements of nitrogen fixation by winter and summer legumes in the Hill and Terai regions of Nepal     

S. L. Maskey  S. Bhattarai  M. B. Peoples  D. F. Herridge 《Field Crops Research》2001,70(3):540-221

Results are reported from on-farm surveys of N₂ fixation in Nepal, conducted between 1994 and 1999, involving the summer legumes soybean, mashbean and groundnut, and the winter legumes lentil and chickpea, at various locations in the Hill and Terai regions of Nepal. Additional less-detailed data were also collected for pigeonpea, grasspea and fababean. There were a total of 107 crops in the major and minor surveys. Estimates of the proportion of legume nitrogen (N) derived from N₂ fixation (Pfix) were determined using the natural ¹⁵N abundance method. Mean estimates of Pfix for the various species were 62% (soybean), 47% (mashbean), 57% (groundnut), 78% (lentil), 79% (chickpea), 75% (pigeonpea), 87% (grasspea) and 85% (fababean). Estimates of total N fixed (including roots) were 59 kg N ha⁻¹ (soybean), 28 kg N ha⁻¹ (mashbean), 153 kg N ha⁻¹ (groundnut), 72 kg N ha⁻¹ (lentil), 84 kg N ha⁻¹ (chickpea), 412 N ha⁻¹ (pigeonpea) and 80 N ha⁻¹ (grasspea and fababean). The on-farm measurements of N₂ fixation were generally similar to those of experimental crops in the same areas of the country. Correlation matrices of soil fertility parameters, shoot dry matter and N, and N₂ fixation revealed that the total amounts of N fixed were influenced primarily by crop growth. Based on the above figures, it was estimated that approximately 30,000 t N were fixed annually in Nepal by legumes, valued at US$ 15 million.  相似文献   

不同氮素形态配比对菜用甘薯产量和品质的影响     

李成阳  柴沙沙  刘意  Soviguidi Deka Reine Judesse  王连军  雷剑  程贤亮  杨园园  杨新笋  张文英 《热带作物学报》2022,43(7):1450-1458

菜用甘薯存在产量低、品质差以及在种植过程中由于不合理施肥造成生态环境恶化等问题,因此,针对以上问题开展本研究。氮肥作为农业肥料投入的主要部分,是影响菜用甘薯产量和品质的重要因素,通过设置不同氮素形态配比处理,根据菜用甘薯茎尖产量和品质相关指标的变化,揭示菜用甘薯产量和品质对氮素形态配比的响应机制,为提升菜用甘薯产量和品质的同时减轻因不合理施肥造成环境污染提供理论依据。本研究为大田试验,供试品种为生产上主栽的2个菜用甘薯品种‘福薯18’（F18）和‘鄂薯10号’（E10）,采用两因素裂区试验设计,设5个氮素形态配比处理为：（1）NH₄⁺-N∶NO₃^--N∶CONH₂-N =1∶1∶1 (N₁);（2）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶0∶2 (N₂);（3）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶0∶1 (N₃);（4）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2∶0 (N₄);（5）NH₄⁺-N∶NO₃^--N∶CONH₂-N = 2∶1∶0 (N₅)。研究结果表明,N₄和N₅处理均可显著提高菜用甘薯的茎尖产量、总酚含量、总黄酮含量、可溶性糖含量、苯丙氨酸解氨酶(PAL)酶活性和IbPAL基因表达量;同一时期不同处理间差异显著,随着生育期的不断推进,各项指标的变化呈先升后降的趋势,其中以N₄处理效果更为显著,除可溶性糖含量在N₃处理下最低外,其他各项指标均在N₂处理下最低,由相关性分析证实,总酚、总黄酮和可溶性含量及PAL酶活性与IbPAL基因表达量呈显著正相关,而可溶性糖含量与基因表达量呈负相关,表明可溶性糖含量的变化与IbPAL基因表达无相关性;由氮素形态配比处理可知,相对于N₂和N₃处理,N₄和N₅处理为植株提供了更多的NO₃^--N,由此推断NO₃^--N在菜用甘薯生长发育过程中起到更为重要的促进作用,而CONH₂-N在本研究中对甘薯产量和品质的促进作用并不突出。而N₄处理即NH₄⁺-N∶NO₃^--N∶CONH₂-N = 1∶2∶0的配肥方案是促进菜用甘薯产量和品质提升的最佳配施组合。本研究结果可为合理配肥以获得理想的作物产量和品质提供理论依据,为在其他作物上开展相关研究提供参考。  相似文献   

Responses of wheat and barley to liming on a sandy soil with subsoil acidity     

C. Tang  Z. Rengel  E. Diatloff  C. Gazey 《Field Crops Research》2003,80(3):235-244

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 (pH_CaCl2 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   

Recovery of nitrogen from different sources following applications to winter wheat at and after anthesis     

M.J. Gooding  P.J. Gregory  K.E. Ford  R.E. Ruske 《Field Crops Research》2007,100(2-3):143-154

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   

Cynodon dactylon control with tillage and glyphosate     

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   

Yield constraints of rainfed lowland rice in Central Java, Indonesia   总被引：1，自引：0，他引：1  

A. Boling  T. P. Tuong  S. Y. Jatmiko  M. A. Burac 《Field Crops Research》2004,90(2-3):351-360

The low and unstable yields of rainfed lowland rice in Central Java can be attributed to drought, nutrient stress, pest infestation or a combination of these factors. Field experiments were conducted in six crop seasons from 1997 to 2000 at Jakenan Experiment Station to quantify the yield loss due to these factors. Experimental treatments—two water supply levels (well-watered, rainfed) in the main plots and five fertilizer levels (0-22-90, 120-0-90, 120-22-0, 120-22-90, 144-27-108 kg NPK ha⁻¹) in the subplots—were laid out in a split-plot design with four replications. Crop, soil, and water parameters were recorded and pest infestations were assessed.

In all seasons, rice yield was significantly influenced by fertilizer treatments. Average yield reduction due to N omission was 42%, to K omission 33–36%, and to P omission 3–4%. Water by nutrient interactions did not affect rice yield and biomass production. In two of the three dry seasons, an average of 20% of the panicles were damaged by pests and estimated yield loss from pests was 56–59% in well-watered and well-fertilized treatments. In one out of six seasons, yields under rainfed conditions were 20–23% lower than under well-watered conditions. Drought, N and K deficiencies, and pest infestation are the major determinants for high yields in rainfed environments in Jakenan. Supplying adequate nutrient and good pest control are at least as important as drought management for increasing crop productivity of rainfed rice-growing areas in Central Java. The relative importance of drought, nutrient and pest management may vary in other rainfed areas. Yield constraints analysis should be systematically carried out to identify appropriate management strategies.  相似文献   

Comparative effects of food processing liquid slurry and inorganic fertilizers on tanner grass (Brachiaria arrecta) pasture: grass yield,crude protein and P levels and residual soil N and P          下载免费PDF全文

M. St. Luce  G. G. Gouveia  G. D. Eudoxie 《Grass and Forage Science》2017,72(3):401-413

This small‐plot field study evaluated food processing liquid slurry (FPLS) as a potential fertilizer for tanner grass (Brachiaria arrecta) production on an acidic loam soil. The treatments, arranged in a randomized complete block design with three replicates, consisted of an unfertilized control, inorganic fertilizer applied at 50 and 200 kg nitrogen (N) ha^?1 with and without phosphorus (P) at 50 kg P ha^?1, and FPLS applied at 50 and 200 kg N ha^?1. Compared to the unfertilized control, the FPLS applied at 200 kg N ha^?1 significantly increased grass dry‐matter yield (DMY), herbage crude protein (CP) and P content, and N and P uptake in the second of two trials and P uptake in both trials. However, DMY and contents, of CP and P were generally lower for the FPLS treatments compared to the inorganic fertilizers. Apparent N recovery was higher for the inorganic fertilizer treatments than FPLS treatments in trial 1, while apparent P recovery was similar among all treatments in both trials. The FPLS treatments did not significantly increase soil NO₃‐N and P concentrations, but increased NH₄‐N in the 0–15 cm layer. The results suggest that application of FPLS to tanner grass pastures is an alternative to its disposal in landfill.  相似文献   

Yield and water productivity of rice–wheat on raised beds at New Delhi, India     

B.U. Choudhury  B.A.M. Bouman  A.K. Singh 《Field Crops Research》2007,100(2-3):229-239

Permanent raised beds are being proposed for the rice–wheat system in the Indo-Gangetic Plain to increase its productivity and to save water. It is not clear whether reported water savings in rice arise from the geometry of the beds per se or from the particular water management that keeps the soil in aerobic conditions and that can also be applied on flat land. Moreover, little research has been reported on direct seeding of rice on raised beds and on the effect of raised beds on the subsequent wheat crop. In this paper we compare the yield, input water (rainfall and irrigation) use and water productivity of dry-seeded rice on raised beds and flat land with that of flooded transplanted and wet-seeded rice, and analyze the effects of beds on the subsequent wheat crop. The experiment was conducted in 2001–2003 at New Delhi, India.

Rice yields on raised beds that were kept around field capacity were 32–42% lower than under flooded transplanted conditions and 21% lower than under flooded wet-seeded conditions. Water inputs were reduced by 32–42% compared with flooded rice, but could also be accomplished with dry seeding on flat land with the same water management. Reduced water inputs and yield reductions balanced each other so that water productivity was comparable among most treatments. Wheat yield was 12–17% lower on raised beds than on flat land with conventional (20 cm) row spacing. Neither wheat nor rice on raised beds compensated for the loss in rows by extra tillering or leaf growth at the edges of the rows. There was no carry-over effect of type of land preparation in rice on the growth and yield of the subsequent wheat crop. Further research on raised beds should focus on the selection of suitable rice and wheat varieties, soil health issues such as nematodes and micro-nutrient deficiencies, weed control, bed stability and long-term carry-over effects from one crop to the other.  相似文献   

Increased frequency of phytosanitary pod removal in cacao (Theobroma cacao) increases yield economically in eastern Peru     

W. Soberanis  R. Ríos  E. Arvalo  L. Zúiga  O. Cabezas  U. Krauss 《Crop Protection》1999,18(10):109-685

Diseases caused by Moniliophthora roreri (moniliasis), Crinipellis perniciosa (witches’ broom) and Phytophthora palmivora (black pod) are the most important factors limiting cocoa production in Peru and cultural management is considered to be the only practical means of control for the smallholder. The objective of this study was to develop an epidemiologically and economically sound control recommendation based on the frequency of phytosanitary pod removal. Weekly removal of diseased pods reduced the incidence of diseases significantly in comparison with fortnightly removal. In three fields, moniliasis was decreased by 26–41%, black pod by 35–66% and witches’ broom on pods by 14–57%. The cumulative effect was a consistent yield increase from an average of 504–660 kg ha⁻¹ yr⁻¹. Returns compensated for increased labour costs. Weekly pod removal was 32% more profitable. Time-course analyses indicated that weekly removal should be practised throughout the year under field conditions of eastern Peru.  相似文献   

The value of catch crops and organic manures for spring barley in organic arable farming     

Jrgen E. Olesen  Elly M. Hansen  Margrethe Askegaard  Ilse A. Rasmussen 《Field Crops Research》2007,100(2-3):168-178

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   

N-use efficiency of single, double and synthetic maize lines grown at four N levels in three ecological zones of West Africa   总被引：1，自引：0，他引：1  

H. A. Akintoye  J. G. Kling  E. O. Lucas 《Field Crops Research》1999,60(3):208-199

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   

Rice yield and productivity gaps in irrigated systems of the forest zone of Côte d'Ivoire     

Mathias Becker  David E. Johnson 《Field Crops Research》1999,60(3):367-208

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   

Mineral concentrations in herbage and soil in a Pinus radiata silvopastoral system in north-west Spain after sewage sludge and lime application     

A. Rigueiro-Rodríguez  M. R. Mosquera-Losada  M. L. López-Díaz† 《Grass and Forage Science》2007,62(2):208-224

Silvopastoral systems in north-west Spain can reduce the risk of fires and promote multi-purpose forest land use. Fertilizer application is important for optimal pasture and tree production. The application rate of sewage sludge as a fertilizer is regulated and is based on its nutrient concentration, especially nitrogen. The aim of this study was to assess the effect of three consecutive years of application of different application rates of sewage sludge and inorganic fertilizer, with or without lime (2·5 t CaCO₃ ha⁻¹) on the ammonium, nitrate and exchangeable K, Ca and Mg contents in soil, and on the crude protein (CP), K, Ca and Mg concentrations in herbage in a silvopastoral system established under a 5-year-old Pinus radiata D. Don plantation with a density of 1667 trees ha⁻¹. The experiment was started in autumn 1997, when a pasture mixture was sown (25 kg ha⁻¹ Lolium perenne , 10 kg ha⁻¹ Dactylis glomerata and 4 kg ha⁻¹ Trifolium repens ). Changes in ammonium and nitrate content in the soil in response to liming and sewage sludge application reflected the initial pH of the soil. In general, liming increased the available Ca and Mg content in soil, and CP and Ca concentrations in herbage, but reduced exchangeable K content in the soil in the first year. Application of sewage sludge increased all of the measured nutrients in both soil and herbage.  相似文献   

Use of Lorenz curves and Gini coefficients to assess yield inequality within paddocks   总被引：1，自引：0，他引：1  

Victor Sadras  Rodolfo Bongiovanni 《Field Crops Research》2004,90(2-3):303-310

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   

Influence of different forage grasses on nitrate capture and leaching loss from a pumice soil   总被引：1，自引：0，他引：1  

A. J. Popay  J. R. Crush 《Grass and Forage Science》2010,65(1):28-37

Nitrogen (N) uptake and loss in leachate from a pulse of ¹⁵N-labelled synthetic cow urine applied to a pumice soil were compared in a glasshouse lysimeter experiment among the grass species, Agrostis capillaris , Dactylis glomerata , Phalaris aquatica , Lolium multiflorum , L . perenne and a L . multiflorum/A. capillaris mixture. In addition, four L. perenne treatments investigated the effect of infection by Neotyphodium lolii strains. Leachate volumes and leachate nitrate concentrations were measured. At final harvest 24 weeks after sowing, dry matter (DM) mass of shoots and roots, plant N and ¹⁵N contents, soil residual mineral N, and root diameters and lengths were measured. Endophyte had no effect on plant or nitrate variables. Lysimeters planted with L . perenne (pooled endophyte treatments) leached 48 mg of NO₃-N compared with <3 mg N for the other grasses. Recovery of ¹⁵N was highest in A. capillaris (0·99), followed by D. glomerata and P. aquatica (0·89), the L . multiflorum / A. capillaris mixture (0·87), L . multiflorum (0·60) and L . perenne (0·44). Low ¹⁵N recoveries and high leaching losses from L . perenne were associated with low plant and root masses of DM and low rooting depth. High aerial mass of DM, root systems extending below 20 cm and high root masses of DM in lysimeters with A. capillaris , P. aquatica and D. glomerata contributed to a high rate of nitrate interception by these species and low leachate losses. The L . multifloru m/ A. capillaris mixture was intermediate between the two species for most of the variables measured.  相似文献