籽粒苋不同富钾基因型根际钾营养与根系特性研究

在缺钾土培和水培条件下,研究了籽粒苋不同基因型根际和非根际土壤速效钾、缓效钾和全钾含量的变化,以及根际微生物数量、根系主要分泌物、根系质子分泌量和根系CEC的变化。结果表明,籽粒苋根际土壤速效钾和缓效钾含量明显高于非根际土壤,且在根际形成钾的相对富集区,富钾基因型R104和K12根际钾的富集能力明显高于一般基因型;籽粒苋根际土壤的全钾含量却低于非根际土壤,富钾基因型的降低幅度大于一般基因型。富钾基因型根际微生物数量和根系分泌能力显著高于一般基因型,且根际细菌和真菌数量与主要根系分泌物的分泌量变化基本保持一致。富钾基因型R104和K12根系CEC和H 分泌量高于一般基因型M9和Cr047,而相同基因型内各品种间的变化不显著。     

不同钾肥对再生水灌溉条件下土壤-作物系统Cd的影响

为了探明再生水灌溉条件下不同施钾肥处理对土壤-作物系统Cd的影响及差异性,通过田间微区试验研究了不同施钾肥处理对再生水灌溉番茄植株、果实以及根际土与非根际土Cd含量的影响。结果表明:再生水灌溉条件下,施钾肥处理可提高番茄果实产量,施加KCl较K2SO4增产效果明显,分别较不施肥处理可增产6.10%～24.00%和1.36%～13.16%;不施钾肥较不施肥处理番茄果实Cd含量降低,但降低幅度小于施加钾肥处理,施加KCl较K2SO4处理番茄果实Cd含量较低,Cd含量分别较不施钾肥处理分别减少58.33%和8.33%,且各处理均未超0.05mg/kg的限值标准;不施钾肥处理较不施肥处理土壤pH、Cd含量有所降低,降低幅度小于施钾肥处理,有效态Cd有所增加,施加KCl和K2SO4较不施肥处理有效态Cd降低,施加KCl和K2SO4较不施钾肥处理根际土和非根际土pH、Cd含量和有效态Cd含量均有所降低,其中施加KCl根际土和非根际土Cd含量分别降低2.96%～3.11%和5.75%～14.22%,施加K2SO4分别降低4.14%～5.90%和8.10%～8.29%;施加KCl根际土和非根际土有效态Cd含量分别降低10.75%～16.19%和13.98%～28.74%,施加K2SO4分别降低15.97%～20.55%和19.91%～24.70%。因此,再生水灌溉条件下,可通过选择施加适宜的钾肥种类,调控重金属Cd在土壤-作物系统的分布及其生物有效性,施加K2SO4较KCl相比,可一定程度降低土壤Cd全量及有效态Cd含量。     

Minimizing the Treatments Required to Determine the Responses of Different Crop Genotypes to Potassium Supply

ABSTRACT

Crop genotypes that make best use of potassium (K) fertilizers can promote agricultural sustainability. However, screening germplasm collections for responses to K fertilizers is often laborious and expensive. To reduce costs, the number of K fertilizer treatments required to identify better genotypes should be minimized. This might be achieved by exploiting the mathematical relationships between biomass, plant K content, and K supply. This study employed 14 barley (Hordeum vulgare L.) genotypes growing in a hydroponics system that allowed the K supply to roots to be controlled through the K concentration in a flowing solution. It sought to determine the minimal number of treatments required to model the relationships between (a) shoot biomass and K supply, (b) plant K content and K supply, and (c) shoot biomass and plant K content. The relationships between (a) shoot biomass and K supply and (b) plant K content and K supply for any given genotype could be fitted by Michaelis–Menten equations and each of these could be estimated from data obtained at two, appropriately-chosen, rates of K supply. The relationship between shoot biomass and plant K content could be estimated from these relationships. However, the optimum K supply required for accurate estimates differed between genotypes and whether shoot biomass or plant K content was to be estimated. It is, therefore, suggested that the relationships between shoot biomass, plant K content, and K supply might best be determined from measurements of biomass and K content at three, carefully-selected, rates of K supply.     

不同用量包膜氯化钾对马铃薯产量、品质及土壤钾供应的影响

利用马铃薯盆栽试验,通过设置不施钾肥、普通氯化钾、30%、50%、70%以及全量(等量于普通氯化钾)包膜氯化钾的处理,研究不同用量包膜氯化钾对马铃薯产量、品质及土壤钾素供应的影响。结果表明:包膜氯化钾25℃静水浸泡的钾素日均释放量约为1.2%,符合控释肥行业标准,在土埋下的钾素释放率呈S型,于70~90天释放率达到最大值,与马铃薯块茎形成及膨大时期相吻合,有利于产量形成;较普通氯化钾,包膜氯化钾的马铃薯增产幅度为13.92%~36.54%;包膜氯化钾全量处理的Vc含量、可溶性蛋白及淀粉含量显著高于普通氯化钾,而包膜氯化钾全量施用的马铃薯还原性糖含量显著低于其他处理,降低幅度为13.9%~36.2%;包膜氯化钾钾素缓慢释放,满足植株后期对钾的需求,在块茎形成期后,包膜氯化钾50%以上用量处理的植株吸钾量显著高于其他处理;包膜氯化钾50%以上用量的土壤速效钾含量在块茎形成期后显著高于通氯化钾,同时,土壤水溶性钾与非特殊吸附钾含量较普通氯化钾分别增加8.4%~25.1%和9.3%~36.1%,土壤钾素供应充足。综上,包膜氯化钾50%以上用量有利于提高马铃薯产量、商品薯率和品质,同时增加土壤钾素供应。     

Interrelations in Phosphorus and Potassium Accumulation Characteristics of Plants Grown in Different Soil Types

Nutrient accumulation characteristics and mineral content of plants depend on several factors such as crop and site characteristics, environmental conditions, and soil nutrient levels. Nutrient interactions are rather complex and may have an important role in this context. It is evident that phosphorus (P)–potassium (K) interaction is a part of cation–anion balance in plants. Although several authors demostrated the positive P-K interaction in plants, results are still inadequate. Studies on P-K interaction and adequate P/K ratios are needed to improve nutrient efficiency. Pot experiments were carried out under greenhouse conditions with perennial ryegrass (Lolium perenne L.) grown in three soils different in texture, soil organic matter (OM), pH, and available nutrient levels: an Eutric cambisol, a Calcaric fluvisol, and a Haplic phaeosem. Soil samples were taken from selected plots of National Long-Term Fertilization Trials (NLFT) after 30 years of fertilization. Besides the unfertilized control, increasing rates of P were applied in four replicates at four levels of P supply resulting from long-term P fertilization. Dry-matter (DM) production, P and K accumulation characteristics, nutrient concentrations, and K/P ratios of perennial ryegrass were studied for 4 months by taking four cuts. From the results, it was evident that both P and K accumulation of plants were closely related to DM accumulation. Phosphorus accumulation characteristics and amounts of P taken up by plants responded both to the level of long-term P supply and to rates of freshly applied P. Better levels of P supply had a beneficial influence on K uptake and K concentrations in plants. Phosphorus concentrations ranged between 0.20% and 0.53% P, whereas concentrations of K were between 1.63% and 5.64%. As the interaction between P and K may influence that of other nutrients, further research is needed to identify these relationships.     

控释钾肥对玉米产量、钾肥利用率和土壤速效钾的影响

通过玉米—小麦轮作条件下连续2年的大田定位试验,以钾空白(CK)、普通氯化钾常量(K1)、普通氯化钾高量(K2)为对照处理,研究通过控释氯化钾常量(CRK1)、控释氯化钾高量(CRK2)、氯化钾与控释氯化钾等比掺混常量(BBF1)、氯化钾与控释氯化钾等比掺混高量(BBF2)处理对玉米产量、钾肥利用率和土壤速效钾的影响。结果表明:(1)BBF2玉米-小麦季产量分别为11 697.8kg/hm2和11 921.1kg/hm2,增产和增收效果最好,较K1分别显著增产13.3%和15.7%,较K1分别显著增收16.6%和19.6%;(2)BBF2钾肥农学利用率较K1分别显著提高了49.0%和41.9%,生理利用率较K1分别显著提高了17.6%和34.8%;BBF1钾肥表观利用率最高,玉米—小麦分别为23.73%和35.22%;(3)施用钾肥显著提高了玉米的株高和茎粗;BBF2提高了玉米吐絮后期至成熟期的株高;CRK1、CRK2、BBF1、BBF2均提高了玉米吐絮后期叶片SPAD值。本试验条件下,控释氯化钾与普通氯化钾掺混施用可满足玉米整个生育期的钾素需求,提高玉米产量和钾肥利用率,BBF2处理为玉米最佳钾肥施用方案。     

Potassium Substitution by Sodium in Root Medium Influencing Growth Behavior and Potassium Efficiency in Cotton Genotypes

ABSTRACT

Potassium (K) deficiency affects cotton (Gossypium hirsutum L.) growth. Sodium (Na) can substitute K for some non-specific functions in plants. Four cotton genotypes were evaluated for their growth rates and K use efficiency grown at various K:Na. The cotton genotypes and treatments had significant (p < 0.01) effect on biomass production, growth rate related parameters, K use efficiency, and K: Na ratio. Maximum total dry matter (2.57 g plant^-1) was accumulated by ‘NIBGE-2’ and minimum (1.91 g plant^?1) was by ‘FH-1000’. Maximum K:Na ratio in shoot was obtained by ‘MNH-786’ and minimum was by ‘NIBGE-2’when 1/3rd K was replaced with Na. Genotypes and various treatments significantly (p < 0.05) influenced specific utilization rate (SUR) and K transport rate (KTR). There was a significant relationship (R² = 0.84, n = 60) between shoot dry matter and K: Na ratio in shoot. Overall, the growth was better when K and Na were added in ratio of 3:1.     

钾高效基因型棉花的筛选及其生理机制的研究

通过营养液培养,设缺K和适K处理,进行棉花苗期培养,以苗期干物质的K效率系数(-K/ K)评价K效率差异,从86个不同系谱的棉花品种中分次逐步筛选,获得4个候选品种.对候选品种进行全生育期土培试验,设施K和不施K处理,获得皮棉产量,以皮棉产量的K效率系数(-K/ K)来反映品种间的K效率差异,确定103为K高效高潜力基因型,122为K低效低潜力基因型,163和165为K高效低潜力基因型.103具有较强的吸收土壤速效K、活化土壤缓效K的能力,并以较低的K含量往繁殖器官运输分配,建成较多的子棉和皮棉,这可能是其K高效的机制之一.     

中国稻作区土壤速效钾和钾肥偏生产力时空变化

基于农业农村部布置在全国的水稻土监测样点(1988—2017),分析不同稻作区水稻土的速效钾、钾肥偏生产力和钾素表观平衡的时空变化趋势.在30 a间,东北区水稻土速效钾含量显著高于长江三角洲(长三角)、长江中游、华南和西南地区.随试验年限的延长,除了长江中游的水稻土速效钾为先增加后稳定的趋势外,东北、长三角和华南区的水...     

不同播期和环境条件对籽粒苋生长及富钾能力的影响

本文通过单因素试验 ,研究了不同环境因素 (温度、CO2 、水分、施肥等 )对籽粒苋生长发育及其富钾能力的影响。研究结果表明 :(1)籽粒苋在籽粒苋生长期内 ,以 7月 12日和 2 2日播种的籽粒苋 (日均温为 2 6.9～ 2 6.2℃ )生长最好 ,相应的植株含钾量也最高。 (2 )当大气中的二氧化碳浓度达到 10 0 0 μl/L时 ,籽粒苋的平均株高、单株平均鲜重和植株平均含钾量 (K2 O)较对照均有显著增加。 (3 )土壤水分条件以田间持水量对籽粒苋生长最为合适 ,低于田间持水量则影响植株对钾的吸收。 (4 )籽粒苋属于在多钾、缺钾土壤上 ,吸钾能力强的植物类型 ,施用钾肥有利于提高籽粒苋植株的含钾量     

渭北旱塬梯田土壤钾素状况及影响因素分析

对渭北旱塬梯田土壤钾素特征、剖面变异性及影响因素的系统研究表明,表层各形态钾素中有效性钾和速效钾的空间变异性最大,钾素分布并不平衡;整体来看,因富钾矿物的作用导致钾储量（矿物钾和全钾）充盈,但约95％对植物长期无效;有效钾素（有效性钾和速效钾）的供应及潜在给源（缓效钾）都较富足。在80cm剖面内,各形态钾素的变异性既反映出它们之间可相互转化,也揭示出梯田植物受钾素影响的范围在60cm以内。有机质、CEC和粘粒对有效钾素影响较大CaCO3和pH值对各形态钾素呈负效影响,特别是CaCO3对缓效钾的“稀释效应”最为明显;坡位、坡向和梯田类型对土壤钾素都有一定程度的影响;研究区梯田耕种至少17年以上钾素开始衰退,但降幅较小。     

渭北旱塬梯田土壤钾素状况及影响因素分析

对渭北旱塬梯田土壤钾素特征、剖面变异性及影响因素的系统研究表明,表层各形态钾素中有效性钾和速效钾的空间变异性最大,钾素分布并不平衡;整体来看,因富钾矿物的作用导致钾储量(矿物钾和全钾)充盈,但约95%对植物长期无效;有效钾素(有效性钾和速效钾)的供应及潜在给源(缓效钾)都较富足。在80 cm剖面内,各形态钾素的变异性既反映出它们之间可相互转化,也揭示出梯田植物受钾素影响的范围在60 cm以内。有机质、CEC和粘粒对有效钾素影响较大;CaCO3和pH值对各形态钾素呈负效影响,特别是CaCO3对缓效钾的"稀释效应"最为明显;坡位、坡向和梯田类型对土壤钾素都有一定程度的影响;研究区梯田耕种至少17年以上钾素开始衰退,但降幅较小。     

包膜含缩节胺氯化钾对棉花产量及土壤钾素的影响

棉花是具无限生长特性的喜钾作物,为解决其生育期内多次追施钾肥和叶面喷施缩节胺的用工问题,实现轻简化种植目标,研究包膜含缩节胺氯化钾对棉花产量、经济效益和土壤钾素变化特征的影响。试验设5个处理,分别为一次基施180kg·hm^-2包膜含缩节胺氯化钾(CRKMC)、减少30%钾素用量(126kg·hm^-2)的包膜含缩节胺氯化钾(70%CRKMC)、基施180 kg·hm^-2普通包膜氯化钾(CRK)、分次施用180 kg·hm^-2普通氯化钾(KCl)和对照(CK,不施钾肥),后三个处理叶面喷施三次缩节胺。结果表明:等量施钾条件下,CRKMC和CRK较KCl籽棉产量分别增加8.81%和9.36%,经济效益分别增加15.53%和12.86%,70%CRKMC较KCl增产6.53%,增加净收入13.64%。CRKMC抑制棉花盛花期前的株高,提高后期株高、茎粗和叶绿素含量,使生物量较KCl增加18.56%～24.98%,提高钾素吸收量,表观利用率增加25.06～38.83个百分点。CRKMC中的钾素和缩节胺在土壤中...     

蕺菜属植物富钾基因型的筛选

在低钾土壤培养和营养液培养的条件下,采用植株含钾量、吸钾速率和钾素利用率并结合植株根系形态特征,对蕺菜属(Houttuynia Thunb.)16份不同基因型材料的富钾能力进行筛选.结果表明,峨眉蕺菜W01-86以及蕺菜W01-34和W01-71在低钾土壤培养和溶液培养时植株含钾量分别高于9.0%,5.50%,吸钾速率大于1.50μmol/(g·h).低钾土壤培养和溶液培养时的钾素利用率分别高于2.50,0.30g/g,为富钾基因型;W01-4和W01-99低钾土壤培养和溶液培养时的植株含钾量分别低于8.5%,5.0%,吸钾速率小于0.65μmol/(g·h),低钾土壤培养和溶液培养时的钾素利用率分别低于2.00,0.30 g/g,为低钾基因型.     

成都平原西部土壤速效钾含量剖面分布特征及其影响因素

为了准确获取土壤钾素剖面分布信息,掌握区域钾素运移和合理精准施肥的需要,基于134个剖面(0—100 cm)采样数据,运用经典统计学和地统计学方法探讨了成都平原西部土壤速效钾剖面分布特征,并对比分析了成土母质、土壤类型和土地利用方式对土壤速效钾剖面分布的影响。结果表明:土壤速效钾含量在水平方向上具有一定的规律性,其高值密集在金马河以南的崇州、邛崃和大邑区域,而低值出现在都江堰—郫县—温江一带,低值区面积占研究区面积50%以上,总体呈现由西南部向东北部显著降低趋势。垂直方向上0—100 cm随土层逐渐降低,表层土壤显著高于下层土壤(P0.05),下层土壤变幅(最大值与最小值之差)随土壤深度的增加逐渐减小。0—100 cm不同土层块金系数均为25%～75%,表现为中等程度空间自相关性,受结构性因素和随机因素共同影响。表层土壤速效钾空间分布受成土母质、土壤类型和土地利用方式共同影响,土壤类型的解释能力最高,分别是成土母质和土地利用方式的1.97,2.58倍;下层土壤主要受成土母质和土地利用方式的影响,影响程度均随着土层深度的增加而增加,相较之下,母质的影响程度增加更为显著。总体来看,成土母质和土地利用方式是影响研究区土壤速效钾剖面分布的主控因素。     

Differences in Growth and Potassium-Use Efficiency of Two Cotton Genotypes

To study the differences in growth and potassium (K)–use efficiency of two different K-use-efficiency cotton genotypes, a pot experiment was conducted in 2007. Experimental materials include two cotton genotypes (HG103 and LG122) and two K application levels (0 and 0.23 g kg^–1 soil). The initial dates of various growth stages, plant heights, numbers of leaves, squares, and bolls, and the amount of litter during the whole growing season were recorded. The distribution and accumulation of dry matter and K content in various organs were measured to compare the differences in K-use efficiency. Significant differences (P < 0.05) between the two genotypes and K levels were found in initial bolling time. At the reproductive growth stage, the plant heights and leaf number of HG103 were less than those of LG122. Greater numbers of squares and bolls were recorded from HG103 than LG122 with K application. Significant differences (P < 0.05) existed in dry matter and K contents in each organ in the two genotypes and K-application levels. The seed cotton yields of HG103 were 3.24 times larger than those of LG122 with K application and 1.77 times larger than those of LG122 with the marginal K treatments. Reproductive-to-vegetative ratios (RVR) and harvest indices (HI) of LG122 were less than those of HG103 whether K was applied or not. The ratios of K in reproductive organs to vegetative organs for LG122 were 0.47 and 0.51 with K application and the marginal treatments, respectively, and for HG103 were 0.66 and 0.75 respectively. The K accumulations in root, stem, and litter of LG122 were more than those of HG103, whereas those in leaves and bolls were less than those of HG103. These results indicated that HG103 transferred more photosynthesis products and K to cotton reproductive organs than LG122.     

不同园林植物土壤呼吸及影响因子特征

以郑州市4种园林植物（合欢、龙爪槐、紫叶李和海棠）为试材,采用动态密闭气室红外CO₂分析仪（IRGA）法测定了不同园林植物土壤根区土壤呼吸特征,并通过测定园林植物根区土壤养分含量和酶活性等土壤环境因子（土壤温度和湿度等）,研究不同园林植物根区土壤呼吸影响因子,为城市园林植被建设及景观配置提供科学依据。结果表明:（1）不同园林植物大气温度的日变化趋势均为单峰曲线;大气湿度日变化均呈“V”字形变化趋势;0—10 cm土壤温度与大气温度变化趋势相一致,在14:00左右达到峰值;土壤湿度均呈“V”字形变化趋势,在14:00达到最低,此后有所回升;（2）在日变化尺度上,4种园林植物土壤呼吸均表现为单峰型,且峰值出现的时间基本一致,在14:00左右达到最大,最低值出现在早上6:00,相同时间土壤呼吸速率基本表现为合欢 > 龙爪槐 > 紫叶李 > 海棠;（3）4种园林植物土壤呼吸与土壤温度和土壤湿度之间关系以指数方程拟合最好;（4）4种园林植物土壤养分含量和土壤酶活性的变化趋势相一致,表现为合欢 > 龙爪槐 > 紫叶李 > 海棠,而4种园林植物根区土壤全磷含量差异不显著（p > 0.05）;（5）偏相关性分析可知,不同园林植物土壤呼吸均与土壤养分和土壤酶活性呈现出一定的相关性,其中合欢和龙爪槐的相关系数高于紫叶李和海棠。     

长期施用氮磷肥对(土娄)土钾素的影响

以长期定位施肥与小麦一玉米轮作田间试验为平台,研究了施肥对(土娄)土土壤钾素的影响以及冬小麦生育期内(土娄)土土壤速效钾、缓效钾及微生物量钾的变化.结果表明:氮磷肥不同施用量对土壤全钾基本没影响,而对速效钾、缓效钾及微生物量钾的影响较大.土壤速效钾和缓效钾均随施肥量的增加而减少,而微生物量钾随施肥量的增加而增加,且0-20 cm土层土壤速效钾、缓效钾及微生物量钾含量均高于20-40 cm土层.小麦生育期内,土壤速效钾和微生物量钾含量的变化一致,均是先上升再下降,再上升,又下降的变化.土壤中微生物量钾与有机碳、全氮均呈显著正相关关系,而与土壤速效钾和缓效钾无显著相关关系.氮磷肥在一定施用量范围内,促进了土壤无机态钾素的消耗,而提高了土壤微生物量钾的含量.土壤钾素的这种变化是作物吸收、施肥等因素共同作用的结果.     

连续秸秆还田对水稻土中钾素形态的影响

湖北省武穴市、荆州市和武汉市三个水旱轮作长期定位试验的基础上,研究了连续秸秆还田(三地秸秆还田时间分别为9、5和3年)对不同层次(0~20 cm和20~40 cm)土壤中各形态钾素(水溶性钾、特殊吸附钾、非特殊吸附钾、非交换性钾、矿物钾、全钾)的影响。结果表明:秸秆还田能显著增加0~20 cm土层中特殊吸附钾和非特殊吸附钾的含量,两者的增量分别为9.92%~138.35%和35.57%~143.79%,其中武穴试验点的增加效果相对最好。20~40 cm土层,各处理之间变化规律不明显。土壤全钾含量表现为武穴试验点最低(2.59~3.15 g kg~(-1)),与荆州和武汉试验点差异性较大(9.45~11.91 g kg~(-1))。武穴和荆州试验点供钾能力较低(速效钾含量100 mg kg~(-1)),武汉试验点供钾能力为中等(速效钾含量在100~150 mg kg~(-1))。矿物钾和全钾呈极显著正相关(武穴、荆州和武汉试验点的相关系数分别为0.994**、0.999**、1.000**),速效钾中各组分与速效钾的相关性在三个试验点存在差异,其中还田时间越长相关性越好。     

Evaluation of Adsorption Isotherm Models for Potassium Adsorption under Different Soil Types in Wolaita of Southern Ethiopia

Adsorption isotherm is essential for predicting its mechanisms, which are important for potassium (K) fertilizer application and to recommendation appropriate rates for acidic soils. Thus, the objective of this study was to evaluate K adsorption characteristic of the selected soils by comparing different adsorption models with soil properties of the soil in different districts (Sodo Zurie, Damot Gale, Damot Sore and Boloso Sore) in the Wolaita Zone of Southern Ethiopia. Four adsorption isotherms are: Langmuir, Freundlich, Temkin, and Van Huay were used to describe adsorption processes. Composite surface (0-20 cm) depth soil samples from four districts sites were collected. The results revealed that the K adsorption data coincide with both models with (r² = 0.99). However, Freundlich model was better in describing K adsorption than the other model. The adsorption maxima(ad_(max), distribution coefficient, buffer capacity (BC), and adsorption capacity(a_(capacity) values of soils ranged from -333 to334.5,0.54 to78.7,159.9 to 389.3, and 327 to 417mg Kkg^-1 respectively, these results showed that Sodo Zurie, Bolos Sore and Demote Sore were effective model parameters. Van Huay a_(capacity) 417mg Kkg^-1 while the bonding energy constant Langmuir is -0.075mg Kkg^-1 in Bolos Sore soil compared to other soils, which were found to be more valuable in discriminating between high K adsorption soils. Correlation between some soil properties with ad_(max) were positively a highly correlated with clay, pH, organic carbon (OC) and exchangeable potassium with r² = 0.92**, 0.93**, 0.95** and 0.96 ** respectively, but negatively correlated with bonding energy with r²= -0.79, -0.80,-0.77 and -0.72 respectively, while calcium carbonate (CaCO3) was very highly correlated with ad_(max) r²= 0.99***). The Freundlich constant, Temkin BC, and Van Hauy a_(capacity) were correlated with CaCO3 content soils with r²=0.12,-0.01,and 0.12,respectively, while slope (1/n) was significantly negatively correlated with soil cation exchange capacity (CEC), CaCO₃, clay contents and exchangeable K and Mg²⁺ with r²= 0.04, -0.67, -0.78, -0.69, and –0.69, respectively. These findings reveal the extent of K depletion in the soils of Wolaita providing a baseline for K rates required for crop production and validation of all models through real-time experiments in the field; this is recommended before the models are used on a large scale basis.