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1.
Abstract

The effect of placement (broadcast versus banded) and level of phosphorus (P) applied as superphosphate at 0 to 450 kg P/ha was measured using the yields of cauliflower (Brassica oleracea var botrytis) on newly cleared Karrakatta sands of low natural P fertility. While there was a significant (P<0.01) yield response to level of P, there was no significant response to fertilizer placement. Phosphorus recovery efficiency by curds (P uptake curds/P applied both in kg/ha) decreased from 0.35 at 20 to 0.09 at 320 kg applied P/ha. Phosphorus recovery efficiency by whole plants decreased from 0.58 at 20 kg P/ha to 0.18 at the highest level. Bicarbonate‐soluble P extracted from the top 15 cm of soil was determined on residual P sites from experiments over two years where P was applied from 0 to 450 kg P/ha. These soil test values were related to yield. The critical soil test values required for 95 and 99% of maximum yield were 40 and 55 (μg/g, respectively. The level of freshly‐applied P required for either 95 or 99% of maximum yield varied from 108 to 175 kg P/ha, respectively at <5 μg/g soil test P to 0 at the critical values. Phosphorus in the youngest expanded leaf at buttoning required for 95 and 99% of maximum yield was 0.46±0.02 and 0.47±0.02%, respectively.  相似文献   

2.
Abstract

Pearl millet and annual ryegrass were continually doubled‐cropped on Olivier silt loam soil for seven years at six levels of N, applied as ammonium nitrate in three applications to millet and in two applications to ryegrass. Forage yields increased as N application rates increased. During seven years at the 0 and 448 kg/ha N rate, millet produced 35% and 95%, respectively, as much yield as it produced at the 800 kg/ha N rate, while comparable values for ryegrass were 19% and 83%. At 448 kg/ha of N the two grasses produced a combined yield of over 20 Mg/ha of dry forage per year. Ryegrass yields following millet were consistently lower than yields previously obtained at this site.

Nitrogen applications consistently increased concentrations of N, Ca, and Mg in both forage grasses, while effects on P and K were variable and S concentrations were unaffected. The amounts of all nutrients removed in the forages were increased as yields increased with N application rates. Nitrate‐N levels considered to be toxic to ruminant animals occurred only where N applications exceeded 170 kg/ha at any one time. In vitro digestibility of each grass was consistently increased by N applications.

The percentage of fertilizer N that was removed in the crops ranged from 66% to 68% for millet and from 35 to 52% for ryegrass as N applications increased up to 448 kg/ha. Residual ammonium and nitrate levels in the top 1.2 m of soil were not increased by N rates of 448 kg/ha or lower. At the 800 kg/ha N‐rate, the apparent N recovery rate decreased and residual ammonium and nitrate levels increased throughout the soil profile.  相似文献   

3.
研究了高寒半干旱区8年肥料定位试验中,磷肥和有机肥在莜麦上的产量效应、土壤磷素的平衡、土壤Olsen-P及各形态无机磷的变化。结果表明,单施磷肥(N0P1)莜麦增产30.8%、单施氮肥(N1P0)增产109.4%、氮肥和磷肥配合(N1P1)施用莜麦增产314.0%;NP间表现出显著正交互作用,NP(N1和P1)交互作用增产86.9%;施用22.5和45.0.t/hm2有机肥分别比N0P0处理增产115.1%和220.1%;施用有机肥基础上增施磷肥无明显增产效应。不同施肥处理土壤Olsen-P和各形态无机磷的增减取决于土壤磷素的积累与消耗量,7年不施磷肥土壤Olsen-P降低3.3mg/kg。施用磷肥和有机肥土壤各形态磷库均有不同程度的积累;土壤磷素积累以无机磷为主,其中Ca2-P和Ca8-P的积累量分别占土壤无机磷变化总量的19.3%和25.4%,Al-P和Fe-P分别占23.8%和14.8%,O-P和Ca10-P共占13.0%。依据土壤磷素收支平衡状况计算出维持土壤磷素平衡的P2O5用量为45.0.kg/hm2。根据肥料效应函数计算出有机肥用量为0、22.5.t/hm2时,P2O5的最高产量用量分别为98.4.kg/hm2和87.4.kg/hm2。  相似文献   

4.
Crop establishment is an important yield factor for pearl millet in the Sahel. Therefore, we conducted a series of experiments to determine the effects of seed size, depth and method of planting, millet variety, pre-sowing tillage, and soil fertilization upon seedling emergence, crop establishment, and yield. All experiments were conducted on a sandy Psammentic Paleustalf in Niger.

For all three millet varieties studied, out of a range of sowing depths from 1 to 7 cm, a sowing depth of 3–5 cm resulted in the highest percentage emergence, the highest above-ground biomass, and most secondary roots. High soil temperatures are common during establishment, typical maximum temperatures at a depth of 1 cm exceed 46°C. The adverse effects of wind erosion were least when sowing in hills; establishment, crop stand survival, and yield were better under hill planting than drilling seed.

Pre-sowing tillage increased initial stands and their survival, the latter also depending on fertility. Thus, improved crop yields result from better stand survival and higher yields per hill. Fertilizer application of 17 kg ha−1 P and 40 kg ha−1 of N tripled grain yields. Ridging without prior tillage and plowing increased grain and stover yields two- to three-fold. In combination with fertilizer application, sixfold yield increases were obtained.

If pre-sowing tillage is considered, then, in view of the time limitations, ridging without prior tillage would be preferable to plowing, as it is a much faster operation giving equally good results in terms of crop establishment and yield.  相似文献   


5.
Fertilizer application, particularly nitrogen (N), is important in cool‐season grass forage production. Subsurface (knife) placement of N often has resulted in higher forage yield and N uptake of tall fescue (Festuca arundinacea Schreb.) compared to surface‐broadcast fertilization, but further studies were needed to indicate whether soil pH, phosphorus (P), or potassium (K) modifies the response. Experiment I tested responses of forage yield and N and P concentration to N, P, and K amount and placement. Two types of fertilizer placement ‐ broadcast and knife ‐ were used with 13, 112, or 168 kg N; 0 or 19 kg P; and 0 or 37 kg K/ha in a factorial arrangement. Yields increased by 53% as N fertilization went from 13 to 112 kg/ha and by 69% as N increased from 13 to 168 kg N/ha. Forage yield was increased 26% from knife compared to broadcast fertilizer placement. P application increased forage production by 13%, but K application had no effect on yield. Forage N concentrations increased by 25% as N fertilization went from 13 to 112 kg/ha and by 38% as N increased from 13 to 168 kg N/ha. Effects of added P and fertilizer placement on N concentration often resulted in interactions among factors. Forage P generally was increased by added P, with some effects of interactions among N rate, P rate, and placement. In Experiment II, fescue responses to N placement were tested where different soil characteristics had been established by previous lime and fertility treatments. Forage yield, N concentration, and N uptake were highest where 9.36 Mg/ha of lime were applied as compared to the control. Previous fertility treatments had no significant (P<0.05) effect. When N was knifed, forage yield was related positively to available soil P but not to pH or K. Yield and forage N concentration and uptake were increased by 20, 11, and 33%, respectively, as a result of knife versus broadcast N application.  相似文献   

6.
Abstract. In the Sahel, promising technologies for agricultural intensification include millet stover mulching and ridging. A four year on‐farm experiment was set‐up in order to assess the effect of various combinations of these two technologies on crop development and yield in a millet (Pennisetum glaucum (L.) R. Br.) ‐ cowpea (Vigna unguiculata (L.) Walp.) intercropping system. Treatments included bare surface, ridging, a surface applied banded millet stover mulch (2 t ha–1) and a banded millet stover mulch (2 t ha–1) buried in ridges. The latter three treatments were implemented exclusively in the cowpea rows, with an annual rotation between the millet and cowpea rows. On bare and ridged plots, millet yields fell below 100 kg grain ha–1 after the first year. This was ascribed mainly to soil acidification and loss of soil organic matter rather than to soil physical constraints or water availability despite extensive surface crusting and high soil penetration resistance and bulk density. Compared to the bare plots, ridging increased cowpea hay production by 330% over the four years which was attributed to lower soil penetration resistance and bulk density but also to a reduction of 0.15 cmol+ kg–1 exchangeable acidity in the ridges. Except during the severe drought year of 1997, millet grain yield in the banded mulch treatment remained fairly stable over time at 526 ± 9 kg ha–1. However, a detailed analysis revealed yield compensation mechanisms between various yield components depending on the timing of occurrence of the abiotic stresses. Cowpea productivity was always higher in buried banded mulch plots than in surface applied banded mulch plots but the former treatment appeared unable to sustain millet yields. This decline was attributed to a greater nutrient uptake by cowpea and more rapid acidification in the buried mulch treatment compared to the banded mulch treatment.  相似文献   

7.
Conventional tillage practices on steep and fragile landscape of Himalayan hills result in significant loss of topsoil during rainy season. Soil erosion in Nepal mid-hills is the most critical during pre-monsoon season. Many reviews argue that reduced tillage could be an option to tackle this problem. However, very few field experiments to evaluate reduced tillage systems have to date been conducted in this region. Thus, a field experiment was initiated in factorial randomized complete block design on acidic sandy loam soil (Lithic Dystochrept) during the summer season of 2001 at Kathmandu University (1500 masl) to assess the effects of tillage and cropping patterns on soil and nutrient losses, crop yield and soil fertility. Two main treatments viz. conventional and reduced till, and two sub-treatments viz. sole maize (Zea mays) and maize + soybean (Glycine max) were considered. Soil organic carbon (OC), total nitrogen (N), plant available phosphorus (P) and exchangeable potassium (K) were determined for the original soil and eroded sediment using standard methods. Two years of data indicated annual soil and nutrient losses to be significantly lowered by reduced till as compared to conventional till. Total annual soil loss from conventional and reduced till was 16.6 and 11.1 Mg/ha, respectively. Similarly, annual nutrient losses associated with the eroded sediment were 188 kg OC/ha, 18.8 kg N/ha, <1 kg P/ha and 3.8 kg K/ha for conventional till and 126 kg OC/ha, 11.8 kg N/ha, <1 kg P/ha and 2.4 kg K/ha for reduced till. Soil OC and N losses were significantly higher in conventional till and this may be one of the major causes of fertility depletion in the Nepalese hills. Soil chemical properties did not differ due to tillage and cropping systems; however, over years pH, N and P were increased irrespective of treatments. Although treatments were at par for maize grain yield, conventional till + soybean produced highest grain yield (4.0 Mg/ha) followed by reduced till + soybean (3.9 Mg/ha) and conventional till sole maize (3.8 Mg/ha). Mixed cropping of legumes and maize do not help conserve soil and nutrient loss in hills of central Nepal. Thus, reduced till could be a viable option for minimizing soil and nutrient losses without sacrificing economic yields in central hills of Nepal.  相似文献   

8.
【目的】 不同生态条件下水稻需要的施氮量和移栽密度不同,研究不同生态条件、施氮量和移栽密度下杂交稻产量及氮、磷、钾养分吸收利用规律,可为不同生态稻区肥料优化管理和合理密植提供依据。 【方法】 以杂交稻旌优 127 为材料,在四川德阳和泸州进行两因素列区田间试验。主区为中氮 (N 120 kg/hm2) 和高氮 (N 180 kg/hm2) 两种施氮量,副区为低密 (12.0 穴/m2)、中密 (16.5 穴/m2)、高密 (22.5 穴/m2) 3 种移栽密度。调查了杂交稻产量及氮、磷、钾的吸收利用规律。 【结果】 德阳土壤全氮、碱解氮、水稻全生育期平均太阳辐射、最高温度、最低温度、昼夜温差、积温均高于泸州点,在德阳点的杂交稻产量、氮、磷、钾吸收量分别较泸州点增加了 19.2%、24.0%、3.3%、9.5%,生产单位稻谷产量所需的磷、钾量较泸州分别减少了 15.2%、8.0%,氮需要量与泸州点相当,杂交稻氮、磷、钾收获指数分别增加了 9.2%、9.4%、5.6%。不同生态条件下杂交稻的氮磷钾吸收特点和利用特性不同。在德阳点,高氮处理较中氮处理杂交稻氮、磷、钾吸收量高但产量低;相同氮水平下杂交稻产量、氮磷钾吸收量随着移栽密度的增加而增加,以中氮高密组合产量较高,为 10.87～11.72 t/hm2,且该肥密组合下成熟期植株体内氮、磷、钾养分吸收量处于中等水平,氮、磷、钾收获指数最高,单位稻谷产量的氮、磷、钾需要量相对较低。在泸州点,杂交稻产量和氮磷钾吸收量在高氮高密度处理最优,产量达到了 9.25～9.85 t/hm2,成熟期植株体内氮、磷、钾吸收量也相对较高,但不同肥密组合之间生产单位稻谷产量的氮、磷、钾需要量差异不显著。 【结论】 生态条件显著影响着杂交稻对氮、磷、钾的吸收利用能力,进而影响作物的生长状况,需要根据具体情况制定施氮量和移栽密度。本试验中,德阳稻区温光资源充足,土壤肥力也较高,最佳肥密组合为 N 120 kg/hm2 和密度 22.5 穴/m2;泸州稻区温光资源略低,土壤肥力水平也不如德阳,其适宜的施氮量为 N 180 kg/hm2,密度为 22.5 穴/m2。   相似文献   

9.
Abstract

Field experiments were conducted on calcareous and non‐calcareous Orthic Black Chemozemic soils over a five year period to study the effect of rates and placements of P‐fertilizer on Canadian rape (Brassica napus L. cv Tower) production. Six rates of P as mono‐ammonium phosphate (MAP) were applied at seeding using four placement methods: i) broadcast and cultivated 10 cm into the soil (BC); ii) banded in the seed row with the seed (PWS); iii) banded 2.5 below and 2.5 cm to the side of the seed (PSS); iv) banded 2.5 cm directly below the seed (PBS). Soil type had no significant effect on rape growth, seed yield and P‐uptake. Rape responded best to P‐fertilizer banded with (PWS) or near (PSS, PBS) the seed. But, placing 15 kg/ha P or greater with the seed reduced seedling emergence; with 25 kg P/ha insufficient plants emerged to justify harvesting. The reduced seedling emergence resulted in reduced seed yield and P‐uptake. Maximum yields were obtained when the fertilizer was banded 2.5 cm away from the seed (PSS, PBS). The BC method produced the least growth, yield and P‐uptake responses of the four methods. Only when broadcast rates of P were in excess of 10 kg/ha did rape dry matter, seed and P‐uptake increase. Banding 10 kg/ha with or near to the seed was equivalent to broadcasting 25 kg/ha in terms of seed yield and P‐uptake. Application of P fertilizer also increased seed protein and oil concentrations.  相似文献   

10.
施氮对杂交谷子产量与光合特性及水分利用效率的影响   总被引：9，自引：0，他引：9  
【目的】随着杂交谷子高产特性的凸显和栽培技术研究的不断深入,确立高产条件下的合理施肥方案具有重要现实意义。本文设定了不同氮素水平,研究施氮量对谷子生物量、产量、光合特性及水分利用效率（WUE）的影响,以确定杂交谷子高产的合理施氮方案。【方法】以张杂5号谷子为对象,采用田间小区试验,设施氮量0、 100、 200、 300（分3次施）、300（分2次施）、400 kg/hm2 共6个氮素水平（N0~N5处理）,通过测定杂交谷子籽粒产量、生物量、农田耗水量和光合特性,分析施氮与杂交谷子产量、光合特性及水分利用效率（WUE）之间的关系。【结果】谷子产量、光合特性及WUE与施氮水平密切相关。不同施氮处理谷子生物量比对照N0处理增加了26.33%~87.21%,处理间差异显著。谷子籽粒产量以N3（300 kg/hm2,分3次施）和 N5（400 kg/hm2）处理较高,分别为8202 kg/hm2和8537 kg/hm2,两处理间差异不显著。各生育阶段谷子的耗水特征变化趋势不同。生育前期耗水变化不明显,拔节-抽穗期谷子农田耗水量以N0处理日均耗水量最大;在生育后期N0处理耗水量最小,N3 耗水量最大。全生育期谷子总耗水量处理间差异较小,以N1（100 kg/hm2）处理总耗水量最大。杂交谷子叶片的净光合速率、蒸腾速率和气孔导度均以N0处理最小,N3处理为最大。籽粒水分利用效率、生物水分利用效率及单叶水分利用效率均以N3处理为最高。本试验条件下,施氮量为400 kg/hm2 时,虽获得了最高产量,但与施用N 300 kg/hm2 差异不显著,且水分利用效率较低,说明高量施氮的增产效果不明显。【结论】氮素的合理使用协调了水氮关系,提高了水分利用效率。同时,施氮还提高了杂交谷子的净光合速率、蒸腾速率和气孔导度。施氮量相同,但施肥时期不同,产量和WUE也差异显著。谷子生育前期大量施肥降低了营养物质向籽粒的转移,产量较低。因此,推荐施氮 300 kg/hm2（分3次施）作为本地区杂交谷子高产高效的合理施氮量。  相似文献   

11.
We conducted a pot experiment using a wheat‐millet rotation to examine the effects of two successive rice‐straw biochar applications on crop growth and soil properties in acidic oxisols and alkaline cambosols from China. Biochar was incorporated into soil at rates of 0, 2.25 or 22.5 Mg/ha at the beginning of each crop season with identical applications of NPK fertilizer. In the oxisols, the largest biochar treatment enhanced soil pH and cation exchange capacity, decreased soil bulk density, improved soil P, K, Ca and Mg availability and enhanced their uptake, and increased wheat and millet yields by 157 and 150% for wheat grain and straw, respectively, and 72.6% for millet straw. In the cambosols, biochar treatment decreased soil bulk density, improved P and K availability, increased N, P and K uptake by crops and increased wheat and millet straw yields by 19.6 and 60.6%, respectively. Total soil organic carbon increased in response to successive biochar applications over the rotation. No difference in water‐soluble organic carbon was recorded between biochar‐treated and control soils. Converting straw to biochar and treating soils with successive applications may be a viable option for improving soil quality, sequestering carbon and utilizing straw resources in China.  相似文献   

12.
施氮对不同土壤肥力下玉米氮素吸收和利用的影响   总被引：26，自引：7，他引：19  
采用田间试验,研究了吉林省高、低肥力条件下不同氮肥用量对春玉米产量及氮素吸收和利用的影响。结果表明,范家屯和榆树试验点的最高产量施氮量分别为N 251和206 kg/hm2,最佳经济施氮量分别为N 227和134 kg/hm2。两试验点的最高产量和最佳经济产量均表现为范家屯试验点高于榆树试验点。适宜增加施氮量可显著提高范家屯低肥力试验点玉米氮素最大吸收速率和吸收总量,提前最大吸收速率出现的天数。玉米收获后030 cm土层残留的硝态氮呈现出随着施肥量的增加而增加的趋势,其中榆树高肥力试验点土壤硝态氮积累明显高于范家屯低肥力土壤。范家屯低肥力试验点氮素的农学利用率、表观回收率和偏因子生产力高于榆树高肥力试验点。范家屯低肥力条件下可通过增施氮肥提高产量; 而榆树高肥力条件下则可通过控制氮肥用量达到提高产量和氮肥利用率的双重目标。  相似文献   

13.
Abstract

Manganese (Mn) deficiency often occurs in crops grown on well‐limed sandy soils of the Atlantic Coastal Plain region of the United States. This study was conducted to compare the responses of established alfalfa (Medicago sativa S.) to various application methods of manganese sulfate (MnSO4) fertilizer. Experiments conducted in farmers’ fields at three New Jersey locations determined the effects of applied Mn on forage yield, tissue Mn concentration, and leaf chlorophyll meter readings. An untreated control was compared to the following treatments: foliar Mn applied once before each harvest, foliar Mn applied twice before each harvest, and a one‐time broadcast Mn application in April Or May at 22.4 kg Mn/ha to the soil surface. The rate of foliar Mn used in 1990 was 1.12 kg Mn/ha and in 1991 was 0.56 kg Mn/ha at each treatment time. Forage yield increases were greater with foliar than soil‐applied Mn but there were no differences between foliar‐applied Mn treatments. Total seasonal forage yields were increased (P<0.05) at all three locations with foliar‐applied Mn but at only one location with soil‐applied Mn. When averaged across all locations, forage yields were 6.4% higher than the control for the foliar‐applied Mn treatments compared to 2.9% higher for the soil‐applied Mn treatment. A Mn concentration of 21 mg/kg was determined as the critical level in the upper 15 cm of alfalfa tissue at the early bloom growth stage. Foliar Mn applied twice between harvests most effectively increased tissue Mn concentrations. Soil‐applied Mn initially increased tissue Mn concentration, but there was little long‐term benefit from this treatment. Applied Mn was observed to improve leaf color and chlorophyll meter readings of Mn‐deficient alfalfa. Results indicate that foliar Mn applied before each harvest was a more effective treatment for correction of Mn deficiency of alfalfa than a one‐time soil application of Mn.  相似文献   

14.
Abstract

Bragg soybeans [Glycine max. (L. ) Merill] were grown under field conditions near Sanford, Florida on a tile‐drained Immokalee fine sand (sandy, siliceous, hyperthermic Arenic Haplaquod). The objectives were: 1) to assess the K and P fertilizer requirements of soybeans grown in central Florida 2) to correlate soil and tissue nutritional levels with extractable soil nutrients and 3) to assess the influence of K application time on yield.

Experimental treatments were four K rates (0, 50, 100, and 200 kg K/ha), three P rates (0, 25, and 50 kg P/ha), and two sidedress K rates (0 and 50 kg K/ha) at early bloom. Treatments were arranged in a randomized complete block design and replicated four times.

Yield increased with each increase in applied K. Statistical maximum yield was obtained on plots which contained 103 ppm double‐acid extractable K during the pod‐filling stage of growth. Tissue K at early bloom exceeded 2.85% at maximum statistical yield. Potassium applied broadcast at early bloom did not significantly influence yield.

This soil contained approximately 390 ppm double‐acid extractable P prior to P application. No significant yield response to applied P was observed, indicating that the original extractable P content of the soil was adequate for the yield level obtained.

The quadratic regression of the ratio equivalents of double‐acid extractable K:Ca + Mg on the same ratio for the plant tissue is highly significant. This expression was a good predictor of tissue accumulation of these nutrients in that the coefficient for determination was 0.68.  相似文献   

15.
Field studies were conducted over a period of years on a virgin sphagnum peat bog in St. Charles, New Brunswick to determine the effect of trace elements on carrot (Daucus carota L.) root yield and nutrient concentration. Addition of the trace elements, boron (B), molybdenum (Mo), copper (Cu), and zinc (Zn), did not affect the marketable carrot root yields, although yields differed significantly from year to year. Addition of B at 10 kg/ha resulted in leaf tissue B concentrations as high as 75 mg/kg. Addition of foliar Mo at 0.14 kg/ha and soil Mo at 0.56 kg/ha raised the leaf tissue Mo concentrations to 3 to 4 mg/kg. Copper applications at 30 kg/ha raised the leaf tissue Cu concentration to 12 mg/kg. Zinc addition at 10 kg/ha did not increase the leaf Zn levels which ranged from 44 to 58 mg/kg. The leaf tissue B, Mo, Cu, and Zn levels as low as 29, 0.17, 4, and 44 mg/kg, respectively, were not related to deficiency of these elements. Such leaf tissue concentrations of B, Mo, and Cu are marginal for optimum crop production on this bog and should be monitored periodically to detect any significant trends through continuous use of this bog in crop production.  相似文献   

16.
施用改良剂对大庆盐碱土的改良效果研究   总被引：3，自引：1，他引：2       下载免费PDF全文
为控制棚室土壤盐渍化进程,实现大庆盐碱土可持续利用。通过田间小区试验,在等量石膏、菌渣及硫酸铝基础上设置不同腐植酸用量处理,与定植前土壤盐分含量、p H值进行分析比较,以明确不同改良措施对盐碱土的改良效果。试验结果表明:施用4种改良剂的处理5(施用纯腐植酸1 050 kg/hm~2+石膏1 050 kg/hm~2+硫酸铝22.5 kg/hm~2+食用菌菌渣30 000 kg/hm~2)使土壤全盐量由试验前的1.665 g/kg降低到0.851 g/kg;p H值由改良前9.32降低到8.35,下降近1个单位,由碱性变为微碱性;与处理1相比,其番茄增产19.2%,每公顷棚室增效50 070.9元。相关分析表明,土壤全盐、p H值降低量均与纯腐植酸施用量呈一元二次回归关系。综上分析,处理5对盐碱土改良效果最佳,番茄产量、效益最高,是大庆盐碱棚室最优化的综合改良施肥措施。  相似文献   

17.
Abstract. Two field trials were established in 1991 to determine the effects on crop yield, N uptake, soil moisture content and heavy metal concentration of applying de-inked paper mill sludge (DPMS) over the period 1991 to 1993. In the first year, during decomposition of the DPMS, N immobilization occurred resulting in loss of cereal yield ( P < 0.05) at low rates of N fertilizer. Approximately 40 kg extra N fertilizer/ha was required per 100t DPMS/ha to compensate for this N immobilization. Soil volumetric moisture content was increased ( P < 0.001) by c. 20% at both sites by 200 and 300t DPMS/ha. DPMS did not significantly increase ( P > 0.05) soil concentrations of total Zn, Cu and Pb. Soil nitrate concentrations after harvest were reduced ( P < 0.01) by c. 17 mg N/kg per 100t DPMS/ha with increasing rates of DPMS up to 200 t/ha. In the second year following the DPMS application, there were no significant effects on grain yield indicating that very little or no N was immobilized. By the third year, the soil N supply was 7 kg N/ha higher where a single dressing of 100t DPMS/ha had been applied compared to the control. This resulted in an overall yield increase of 7% ( P < 0.10). Soil N supply was lower (N.S.) but crop yields were similar ( P > 0.05) to the control where single dressings of 200 and 300t DPMS/ha had been applied.  相似文献   

18.
Abstract

Corn (Zea mays L.) is next to rice as an important food crop grown in South Sulawesi, Indonesia. However, yields obtained by farmers are rather low, around 0.6 to 1.0 ton/ha. Efforts to increase yield have been tried through the application of NPK fertilizers. A study was conducted to determine the effects of N, P and K application on corn yield and what soil constrains, in terms of nutrient elements in the corn plants, exist in the latsols found at Desa Tokka, Sinjai, and South Sulawesi. It was found that application of K significantly increased the growth and corn grain yields on the latosols at Sinjai. Without K, grain yield and the K content in the ear leaf were low. The correlation between grain yield and rate of K shows that an application of 72 kg K2O/ha together with 90 kg N and 80 kg P2O5 per ha produce the best yield of 3.6 tons/ha. The K content in the ear leaf of 1.8% was related to this maximum yield.  相似文献   

19.
Abstract

This study was conducted to ascertain further the need for P and K fertilizers to obtain maximum herbage yields from alfalfa (Medicago sativa L.). Vernal alfalfa was established on a low K Piano silt loam (Typic Argiudoll) soil and topdressed with zero, 22.4, and 44.8 kg/ha of P in autumn of seeding year and with zero, 224, and 672 kg/ha of K as KC1 each autumn. The harvest schedule was three cuts annually at first flower; a schedule widely recommended in the North Lake states. No statistical significance was found for P levels nor for the P x K interaction; significance was found only for K levels. Maximum herbage yield was obtained with 224 kg/ha of K in the first harvest year, but with the 672 kg/ha of K rate in the second harvest year. Herbage K and Cl percentages and amounts removed from the soil increased significantly each year with each increase in K applied. Herbage P and N percentages were decreased significantly with the first increment of K. Residual herbage yields showed dramatically the influence of K fertilization on winter survival. All alfalfa stands with no K fertilization were killed completely. Residual yields and stands increased with each increase in K applied. Yield increase over the control was significant only with the second increment of K, while stands increased significantly with each increase in K applied. These data continue to confirm that high levels of soil K are needed for stand survival as well as for high herbage yields.  相似文献   

20.
长期施氮、磷、钾化肥对玉米产量及土壤肥力的影响   总被引：53，自引：3，他引：53  
以1990年建立的国家褐潮土土壤肥力与肥料效益长期监测基地(北京昌平站)的长期肥料定位试验为研究平台,研究了不同施肥制度对玉米产量和土壤肥力的影响。结果表明,长期均衡地施NPK肥或NPK与有机肥配施,可以显著提高玉米产量和土壤有机质、全氮、全磷、速效氮、速效磷、速效钾等肥力指标,并能提高土壤微量元素的含量;而不均衡施肥(N、NK、NP、PK)导致相应的营养元素的耗竭。相关分析表明,在褐潮土上增施磷肥和有机肥对提高玉米产量具有重要的作用。  相似文献   

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