二元非结构肥效模型构建及其田间试验验证

二次多项式肥效模型假设单位养分增产量与施肥量之间为线性模型,结果导致最高施肥量之前和最高施肥量之后的施肥效应是对称关系。这种模型设定偏误以及模型存在的强烈多重共线性和异方差是建模成功率明显偏低的重要原因。本研究研发二元非结构肥效模型,旨在提高二元肥效模型的适用性。在一元非结构肥效模型基础上,根据植物营养元素功能不可相互替代原理,构建二元非结构肥效模型,并通过氮、磷、钾二元组合的田间肥效试验结果检验新模型的拟合效果和推荐施肥量的可靠性。结果表明,在水稻、花生、马铃薯、毛豆、冬小麦和夏玉米的17个氮磷、氮钾、磷钾二因素肥效田间试验结果中,二元二次多项式肥效模型均能通过统计显著性检验,但典型肥效模型仅占试验点总数的58.8%,模型一次项系数或二次项系数代数符号不合理以及推荐施肥量属于外推的非典型式占41.2%。基于二元非结构肥效模型拟合上述试验结果,同样均能通过统计显著性检验,典型肥效模型的比例占试验点总数的88.2%,非典型式模型(均属于推荐施肥量外推)比例仅占11.8%,建模成功率较二元二次多项式肥效模型提高了29.4个百分点。两种模型的最高产量施肥量之间、经济产量施肥量之间存在显著的线性正相关,但线性回归方程的一次项系数分别仅有0.9153和0.9161,表明当二元二次多项式模型推荐的最高施肥量或经济施肥量每增加1 kg时,二元非结构肥效模型的相应推荐施肥分别仅增加0.915 3 kg和0.916 1 kg,较好地克服了二次多项式模型推荐施肥量偏高的问题。分析表明,二元二次多项式肥效模型是二元非结构肥效模型的简化式和特例,新模型具有更广的适用范围。     

免耕水稻在“3414”试验方案中氮磷钾配施的肥料效应研究

在免耕抛秧种植模式下进行“3414”肥料效应试验,通过建立氮、磷、钾施肥量与产量的回归模型,探索当地水稻的最佳施肥量.结果表明,氮磷钾施用量均为中等水平时,产量和经济效益达到最佳;各类型函数所获得的最佳经济产量表现为一元函数＞二元函数＞三元函数.结合一元、二元、三元肥料效应函数及实际生产而获得的推荐施肥指标:最高产量施...     

运用直线加平台法确定黑土区玉米氮磷施肥量

施肥量的确定一直是玉米高产栽培研究的主要课题之一。分别运用肥料效应函数法和直线加平台法,对按照直线加平台法设计的在黑土上春玉米的田间试验结果进行了统计分析,发现利用直线加平台法设计的田间试验结果也可以用来建立肥料效应函数,并根据肥料效应函数求得相应的施肥量。利用肥料效应函数得到的最高产量推荐施氮量和最大利润推荐施氮量分别为107.4 kg hm-2和103.2 kg hm-2,而最高产量推荐施磷量和最大利润推荐施磷量分别45.5 kg hm-2和41.3 kg hm-2。利用直线加平台法得到氮、磷的推荐施肥量分别为73.9和38.0 kg hm-2,明显低于用肥料效应函数法求得的推荐施肥量。对于肥料效应函数无法处理的试验数据,利用直线加平台法仍然可以对实验数据进行处理并得出实验结果,后者是肥料效应函数法的补充。     

黄土丘陵区旱地肥料效应与合理施肥

综合安塞、定西、米脂、河曲4个试区,多年多项目的田间研究结果,分析了不同肥料的增产效益及肥料利用率,计算了不同类型区主要作物的最高施肥量和最佳施肥量及不同R值下的经济合理施肥量。根据雨量和土壤肥力的差异,将黄土丘陵区分为三大片,提出了不同地区的建议施肥量及施用技术。     

新疆南疆核桃肥料效应及推荐施肥量测算

研究新疆南疆核桃施肥效应与最佳效益的推荐施肥量,为肥料的高效利用提供理论依据。以南疆叶城县为研究区,基于“3414+2”试验方案开展核桃肥料效应研究,并利用一元二次、三元二次肥料效应函数进行拟合,进而优化南疆核桃的N、P2O5、K2O施肥量。结果表明,(1)不同施肥量对核桃的产量影响显著,其中N2P2K2处理的产量、品质显著高于其他处理;不同氮肥处理与核桃产量的相关性显著,而磷肥、钾肥对品质的影响更为明显;(2)三元二次回归肥料效应方程的拟合度显著高于一元二次方程,据此测算的核桃推荐施肥量结果为以核桃产量为主要目标情景下,N、P2O5、K2O最佳施用量分别为0.21、0.59和0.58 kg/株,最佳施肥配比为1.0∶2.8∶2.7,预测最佳产量为8.90 kg/株;而以追求核桃品质为目标时,N、P2O5、K2O最佳施用量范围分别是0.55～0.64、1.37～1.50、0.56～0.62 kg/株。基于“3414”肥效试验和三元二次肥效方程回归测算的氮磷钾推荐施肥量及其配比,可为新疆南疆核桃科学施肥提供理论依据。     

辽宁花生施肥模型试验研究

采用二次回归"3414"试验设计,对辽宁花生种植区的施肥数学模型进行了研究,配置出三元肥料效应函数模型Y=2693.10+360.87N+141.53P+104.95K-9.90NP+12.59NK+31.03PK-62.52N2-31.18P2-30.88K2和一元肥料效应函数模型Y=3065.64+576.51N94.86N2;Y=3395.34+346.48P51.02P2;Y=3099.21+366.55K43.82K2并分别推荐了最高产量为3960kghm-2及施肥量N为51kghm-2;P2O5为56kghm-2,K2O为70kghm-2为肥料研究工作者提供了丰富的施肥信息。     

南安县域甘薯的土壤养分丰缺指标研究

应用"3414"田间肥料试验设计的试验结果,旨在了解南安甘薯产区的N、P、K肥料施用效果,建立县域土壤的甘薯养分丰缺指标,并通过多元二次肥料效应函数寻求甘薯最高产量和最佳经济施肥量。甘薯施用N、P、K肥增产增效较为显著,其增产增收效果NPKNKP,单位肥料效益PNK。南安县域内甘薯的土壤养分丰缺等级指标划分为3级,即当土壤碱解氮、有效磷、速效钾养分含量分别为75 m g/kg、20 m g/kg、65 m g/kg时为低,在75~177 m g/kg、20~40 m g/kg、65~135 m g/kg时为中,177 m g/kg、40 m g/kg、135 m g/kg为高。甘薯推荐施肥量随土壤碱解氮、有效磷、速效钾含量的提高而减少。全市平均,甘薯最高产量施肥量为N 197.43 kg/hm2,P2O563.84 kg/hm2,K2O 226.32 kg/hm2;最佳经济施肥量N 179.74 kg/hm2,P2O561.10 kg/hm2,K2O 212.50 kg/hm2。     

大面积经济施肥的建模与施肥推荐研究

本文通过在河南省封丘县进行的多年、多点田间试验,介绍了大面积经济施肥模型的建立与推荐施肥的理论和应用。研究明确应以正交多项式回归试验设计、平方根模型建立产量-肥料效应函数,以边际报酬率计算推荐施肥量。做到了可根据市场经济变化和农民的具体经济情况灵活地推荐施肥。还介绍了包括环境因子的综合建模以及适合省(市)、县和基层应用的计算机推荐施肥咨询系统。     

2008年绩溪县水稻“3414”肥料效应田间试验报告

通过"3414"回归最优设计原理设置的水稻肥效试验,获得了肥料效应函数方程,由此数学模型得出:理论N、P、K最佳施肥量为纯N 144.38 kg/hm2、P2O5 38.38 kg/hm2、K2O 67.02 kg/hm2,N∶P2O5∶K2O为1∶0.27∶0.46时,最佳经济产量为9146.63 kg/hm2.综合分析不同推荐施肥方法的推荐施肥量,结合当地实际,建议推荐施肥量分别为尿素(N,460 g/kg)总量322.34 kg/hm2、过磷酸钙(P2O5,120 g/kg)314.84 kg/hm2、氯化钾(K2O,600 g/kg)112.44 kg/hm2.     

适宜氮磷钾用量和配比提高油用牡丹产量和出油量

【目的】油用牡丹是我国新兴的木本油料作物,但施肥不平衡严重制约油用牡丹的产量和品质。研究氮、磷、钾不同施肥量和配施比例对油用牡丹产量和出油量的影响,探明油用牡丹高产、优质的适宜氮、磷、钾施用量和配比,对提高油用牡丹的生产效率具有重要的现实意义。【方法】以五年生油用牡丹品种‘凤丹’为试验材料,采用“3414”不完全正交回归设计进行了大田试验。试验地常用施肥量为尿素750kg/hm^2、重过磷酸钙270kg/hm^2、硫酸钾600kg/hm^2。设氮、磷、钾4个施肥水平为0(不施肥)、1(常用量的一半)、2(常用施肥量)、3(常用量的1.5倍)。调查了‘凤丹’产量,分析了籽粒出油量。对‘凤丹’产量进行肥效模型拟合,得出最优经济效益的氮、磷、钾肥推荐施肥量。【结果】1)施用氮、磷、钾肥可改善‘凤丹’单株果荚数、单个果荚重量、果荚直径、百粒重等农艺性状,进而提高‘凤丹’产量;氮、磷、钾肥的施用使‘凤丹’分别增产283.7、276.8和150.6kg/hm^2,增产率分别为55.5%、50.3%和23.5%,增加纯收入分别为7310.4、7494.3和2118.9元/hm^2,农学效率分别为0.96、2.76和0.59kg/kg。2)施肥增产及对产量的贡献率均表现为N>P2O5>K2O,肥料农学效率和增收效果则表现为P2O5>N>K2O,但过量施用氮、磷、钾肥会使产量有所下降,且经济效益和肥料利用效率显著降低,氮、磷、钾肥增产和增收效果以及肥料贡献率均以推荐施肥水平处理的最高,农学效率均以1水平最高。3)施用氮、磷、钾肥通过影响出仁率和种仁含油率来影响产油量,最高出仁率可达65.0%,最高种仁含油率可达32.9%,较对照组分别增加13.0%、12.6%,氮、磷、钾均衡施肥产油量可高达193.3kg/hm^2,三因素对产油量影响大小顺序为N>P2O5>K2O。4)氮、磷、钾肥之间存在明显的交互作用,配合施用能提高肥效和促进‘凤丹’的产量和种仁含油率,任一肥料的过量施用均会导致产量降低。5)使用不同拟合方法建立肥料与‘凤丹’产量效应函数方程,通过对比分析二元二次模型为最适模型,基于该最适肥效模型得出‘凤丹’氮(N)、磷(P2O5)、钾(K2O)的最优推荐施肥量为343.2、109.7、248.4kg/hm^2,适宜的氮、磷、钾施肥比例为1∶0.32∶0.72。【结论】合理的肥料配比和用量是‘凤丹’增产的保障。施用适量的氮、磷、钾肥可提高‘凤丹’农艺性状、产量、出仁率、种仁含油率等指标,进而提高产油量,氮(N)、磷(P2O5)、钾(K2O)的最优推荐施肥量为343.2、109.7、248.4kg/hm^2,适宜的氮、磷、钾施肥比例为1∶0.32∶0.72。     

Stimulation of N2‐fixation in chickpea by gamma irradiation as affected by different levels of ammonium sulfate fertilizer

Abstract

A pot experiment was conducted under natural climatic conditions to study the effect of low doses of gamma irradiation (0, 5, 10, and 20 Gy) on the performance of winter chickpea (Cicer arietinum L.) in the presence of increased supply of ¹⁵N labeled ammonium sulfate (0, 20, 50, and 100 kg N ha^‐1). Presowing seed irradiation produced a significant increase in dry matter production (up to 3 6%) and total nitrogen yield (up to 45%). The stimulative effect of irradiation was more pronounced with the application of NH₄ ⁺‐N fertilizer. Seed irradiation increased the amount of N₂‐fixation by 8–61% depending on the dose and level of NH₄ ⁺‐N fertilizer rate. A 10 Gy was found to be the optimal irradiation dose for enhancing N₂‐fixation. High levels of NH₄ ⁺‐N decreased the percentage and the amount of N₂‐fixation, but did not affect nodule formation. However, the presowing 10 Gy irradiation dose reduced the negative effect of ammonia‐N fertilizer on N₂‐fixation. Therefore, we recommend irradiating chickpea seeds with a 10 Gy dose before planting in soil containing high levels of mineral nitrogen to reduce its negative effect on N₂‐fixation.     

新疆奇台县化肥施用量变化及其与粮食单产的关系

根据新疆奇台县1989～2005年化肥施用量和粮食单产数据,采用趋势线法分析了该县化肥单位面积施用量的时闻序列变化,并采用相关分析对化肥施用量与粮食单产的关系进行探讨.结果表明:奇台县化肥单位面积施用量受粮食价格及化肥价格变化的影响较大,从1989年的65.65 kg·hm-2上升到最大值1998年的196.6kg·hm-2后下降,整个时间序列曲线呈抛物线状,且N、P、K施用比例较为合理,为促进粮食增产发挥了作用.1989～2005年粮食单产与单位面积化肥施用量存在明显的正相关关系,随施肥量的增加,粮食单产也趋于增加,当化肥施用量达到170kg·hm-2时,再增加化肥施用量对粮食的增产效果已不明显.因此,该县今后在粮食种植过程中应防止过量施肥,推广科学施肥,以更大程度地提高粮食产量.     

Effect of silicate fertilizer on reducing methane emission during rice cultivation

Slag-type silicate fertilizer, which contains high amount of active iron oxide, a potential source of electron acceptor, was applied at the rate of 0, 2, 6, 10, and 20 Mg ha⁻¹ to reduce methane (CH₄) emission from rice planted in potted soils. Methane emission rates measured by closed chamber method decreased significantly with increasing levels of silicate fertilizer application during rice cultivation. Soil redox potential (Eh) decreased rapidly after flooding, but floodwater pH and soil pH increased significantly with increasing levels of silicate fertilizer application. Iron concentrations in potted soils and in percolated water significantly increased with the increasing levels of silicate fertilizer application, which acted as oxidizing agents and electron acceptors, and thereby suppressed CH₄ emissions. Silicate fertilization significantly decreased CH₄ production activity, while it increased carbon dioxide (CO₂) production activity. Rice plant growth, yield parameters, and grain yield were positively influenced by silicate application levels. The maximum increase in grain yield (17% yield increase over the control) was found with 10 Mg ha⁻¹ silicate application along with 28% reduction in total CH₄ flux during rice cultivation. It is, therefore, concluded that slag-type silicate fertilizer could be a suitable soil amendment for reducing CH₄ emissions as well as sustaining rice productivity and restoring the soil nutrient balance in rice paddy soil.     

氮肥和接种根瘤菌对豌豆/玉米间作产量和水分利用效率的影响

豌豆/玉米间作是河西绿洲灌区面积最大的间作模式,也是当地重要的高产高效种植模式之一。针对目前氮肥过量施用和豆科作物生物固氮被忽视的实际,2011年和2012年在甘肃省武威市凉州区进行了豌豆/玉米间作大田试验,研究不同施氮量下,豌豆接种根瘤菌对豌豆/玉米间作体系作物籽粒产量和水分利用效率的影响,旨在为河西绿洲灌区豌豆/玉米间作体系节肥、高产的氮肥用量和接菌增产作用提供理论依据。结果表明:施用氮肥对豌豆产量影响不显著。接种根瘤菌后单作豌豆比不接菌处理两年平均增产12.7%,间作豌豆产量比单作两年平均增产61.1%,间作豌豆接种根瘤菌比不接菌两年平均增产4.8%。单作豌豆以施氮量75 kg(N)·hm-2接菌处理的产量最高,达到2 735 kg·hm-2;而且在此施氮量下接菌比不接菌两年平均增产达22.8%。施用氮肥对玉米的增产效果显著,施氮量在300 kg(N)·hm-2时单作玉米产量为14 394 kg·hm-2,间作比单作两年平均增产61.8%;间作豌豆带接菌较不接菌玉米两年平均增产3.3%。土地当量比在不同施氮量和接种根瘤菌的条件下都大于1。豌豆水分利用效率随施氮量增加而减小,最大值为不施氮的12.9 kg·mm-1·hm-2;玉米水分利用效率随施氮量增加先增大后减小,以施氮量300 kg(N)·hm-2处理为最高,达25.0 kg·mm-1·hm-2。综上所述,在豌豆/玉米间作体系中,玉米高产、高水分利用效率的施氮量为300 kg(N)·hm-2,豌豆高产高效的施氮量为75 kg(N)·hm-2。在大田生产中,接种根瘤菌对豌豆和玉米增产作用明显。     

不同钙肥施用量对乌拉尔甘草产量及品质的影响

[目的]通过开展不同钙肥施用量对乌拉尔甘草(Glycyrrhiza uralensis.)产量及品质的影响研究,为甘草的优质高产栽培提供依据。[方法]采用田间小区试验方法,比较不同钙肥施用量对乌拉尔甘草株高、药用成分以及地上和地下部生物量的作用。[结果]钙肥施用量为450~600kg/hm2时,甘草的产量和植株甘草酸及总黄酮的总量最大,过量的施用钙肥对乌拉尔甘草的生长以及有效成分的含量具有抑制作用。[结论]适量的钙肥供应有利于乌拉尔甘草的生长以及乌拉尔甘草中有效成分含量的提高。     

Farmyard manure and chemical fertilizers as a source of nutrients for raspberry

Abstract

A long term field experiment was undertaken in four different sites in Québec for evaluating Newbury raspberry nutrient requirement. Addition of farmyard manure one year before the plot establishment at the rate of 70 tons/hectare, increased the fruit production by 20% over the check plot; its residual effect persists even four years after incorporation. Critical nutrient contents of leaves are shown, maximum yields of this cultivar depending on the plant age and the amount of N‐P‐K application are tabulated. These parameters, in combination with farmyard manure, further increased the fruit production up to 35% when ever soil moisture was well provided. A positive effect of P fertilizer on the fruit production was more pronounced than that of N‐fertilizer on this territory and the response to K fertilizer could be obtained where a farmyard manure was applied.     

Effect of Zinc applied together with compound fertilizer on yield and quality of sugar beet (Beta vulgaris L.)

This research was conducted to evaluate the effect of zinc, added into compound fertilizer in the production process, and zinc applied together with compound fertilizer on yield and quality component of sugar beet in 2009–2010.The treatments consisted of nitrogen, phosphorus and potassium (NPK) (12-30-12) compound fertilizer; 2. NPK (12-30-12) compound fertilizer + zinc sulfate and NPK (10-20-20) + 1% Zn compound fertilizer. Root yield, sugar percentage, white sugar percentage (WSP), white sugar yield (WSY), alpha-amino nitrogen, sodium and potassium concentration were investigated in this study. A total of 5 kg ha^?1 zinc application on sugar beet significantly increased the yield and quality of sugar beet; the rate of increase was in the range of 4.62–6.97% in root yield, 2.09–5.75% in sugar percentage, 2.60–8.03% in WSP and 7.84–13.06% in WSY. NPK (10-20-20) + 1% Zn compound fertilizer and NPK (12-30-12) compound fertilizer + zinc applications increased the sugar beet yield and quality values in both years.     

控释氮肥减量对糜子产量、氮素利用及土壤氮含量的影响

针对黄土高原旱作区糜子生产中氮肥种类单一、肥料利用效率低的问题,本试验以当地习惯施氮尿素N 120kg/hm²(TN)为对照,设置控释氮肥N 120kg/hm²(T1)、108kg/hm²(T2)、96kg/hm²(T3)、84kg/hm²(T4)、72kg/hm²(T5)和不施肥(T0)七个处理,探究不同控释氮肥处理下土壤全氮、微生物量氮、硝态氮和铵态氮含量的变化规律,分析糜子成熟期氮素积累分配、氮素利用效率及产量对控释氮肥的响应,以期为建立旱地糜子控释氮肥一次性基施轻简栽培技术提供支撑。结果表明：与施用尿素相比,等量控释氮肥可以提高糜子抽穗期和成熟期土壤全氮、微生物量氮、硝态氮和铵态氮含量分别达0.38%~5.51%、1.76%~7.63%、5.41%~11.80%和4.04%~14.77%,其中硝态氮和铵态氮含量两年均显著高于TN,随着控释氮肥减量糜子田各形态氮素均呈降低趋势,减氮量达20%以上时土壤硝态氮和铵态氮含量均显著低于TN处理。施用控释氮肥可以提高糜子成熟期氮素积累量1.97%~3.21%,增加糜子氮素向籽粒中的分配比例0.55%~1.18%,控释氮肥减量20%以上时糜子氮素积累量显著低于尿素全量基施处理。与普通尿素相比,控释氮肥提高了糜子氮肥表观利用率、氮肥偏生产力及氮肥农学利用率,增幅分别为3.29%~4.59%、3.88%~4.14%和5.01%~7.63%,其中氮肥偏生产力处理间差异达显著水平,随着控释氮肥减量糜子氮肥表观利用率、氮肥偏生产力及氮肥农学利用率均呈上升趋势。施用控释氮肥通过增加单位面积穗数和穗重显著提高了糜子产量两年分别达3.88%和4.47%,控释氮肥减量20%以下时糜子产量与尿素差异不显著。相关性分析结果表明,糜子氮素积累量与产量呈极显著正相关,氮素利用效率指标与土壤硝态氮含量相关性最强。综上所述,施用控释氮肥较尿素可显著提高糜子生育中后期土壤供氮能力,促进糜子对氮素的吸收利用进而增加产量,且在适量减氮20%时并未显著降低糜子产量,因此控释氮肥在糜子生产中有较大的应用前景及减氮潜力。     

Biochar combined with nitrogen fertilizer affects soil properties and wheat yield in medium-low-yield farmland

Biochar combined with fertilizer as a soil amendment benefits to improving soil fertility, especially soil organic carbon and crop yield. However, the effect of biochar on the improvement of soil properties and crop yield was varied from soil properties and limited for medium–low-yield farmland in the North China. During the completely randomized field experiment, SIX treatments (biochar applied as 0, 15 and 30 t·ha^-1, under 240 and 300 kg N ha^-1 nitrogen fertilizer) were applied in wheat season and examined to reveal changes in the SOC and other properties of 0- to 10-cm and 10- to 20-cm soil layers. The results showed that two years after the application of biochar, a significant increase in the SOC was observed, ranging from 19.52% to 97.50% (p < 0.05) in the 0- to 20-cm soil layer. Wheat yield and SOC content increased with increasing amount of biochar applied under the same amount of nitrogen fertilizer. The content of soil available potassium increased significantly under 30 t·ha^-1 biochar application (p < 0.05). Both biochar and nitrogen fertilizer application could increase wheat yield, and the effect of biochar application for increasing wheat yield was better than that of nitrogen fertilizer. Wheat yield and SOC content increased with increasing nitrogen fertilizer at the same amount of biochar application. The principal component analysis results showed that biochar input, SOC, available potassium and total nitrogen were the key factors affecting wheat yield. Biochar application is a fast and effective measure to improve SOC and wheat yield in medium- and low-yield farmlands.     

Poultry litter effects on unmanaged pasture yield,nitrogen and phosphorus uptakes,and botanical composition

Abstract

The poultry industry must dispose vast amounts of waste, mainly litter (PL), generated during production processes. This study was conducted to investigate the short‐term effects of various rates of PL application, i.e., cumulative 2‐year totals of 9.9, 19.4, 29.3, 39.0, and 48.9 mt ha^‐1, to unmanaged pasture on a Starr clay loam (fine‐loamy mixed thermic Fluventic Dystrochrepts). Dry matter yield, N and P concentrations, and changes in botanical composition were measured on a mixed species, tall fescue (Festuca arundinacea Schreb.) and bluegrass (Poa pratensis L.) pasture. Dry matter yields (r² = 0.99*), N uptake (r² = 0.99*), and P uptake (r² = 0.99*) increased curvilinearly with rate of PL application in both years. Yield increase was attributed to correction of N deficiency in pasture by the PL application. Lower levels of PL increased forage yields in 1992 compared with 1991, due to the residual effect of unmineralized N from PL applied in 1991. Nitrogen concentration in tissue increased with levels of PL application but P tissue concentration was not similarly affected. Based on environmental and economic considerations, the PL application rate of 11.4 mt ha^‐1 in 1991 followed by 8.0 mt ha^‐1 in 1992 was the most effective for pasture renovation when compared with the recommended inorganic N and P fertilizer rate. Forage yields on this treatment were 21.5 mt ha^‐1 versus 21.7 mt ha^‐1 for the inorganic N and P fertilizer treatment. All rates of applied PL increased the percentage of tall fescue (from approximately 50 percent to > 80 percent) and decreased the percentage of bluegrass in this mixed pasture. Rates of PL application of 22.9 mt ha^‐1 and above temporarily depressed plant growth. This research indicates that PL properly tested and applied at appropriate rates is a suitable source of fertilizer for pasture renovation and production.