Effect of fertility ratios on growth and turf quality of perennial ryegrass (Lolium prenne L.) in winter

Perennial ryegrass (Lolium prenne L.) has been introduced to Japan as a cool season turfgrass. In spite of relatively mild winter in most parts of the country, it still goes to winter dormancy. A well‐balanced fertility ratio and rate may prevent such dormancy without causing winter injury. Therefore, this experiment was designed to find a balanced rate and ratio among nitrogen (N), potassium (K), and phosphorus (P) fertilizers in order to prevent winter dormancy and promote growth during the winter in Japan. Yorktown 2 perennial ryegrass was used in this experiment. Nitrogen and K application rates were 50, 150, 250, 350, 450, 550, and 650 kg K/ha; whereas P rates were 50, 150, and 250 kg P/ha. These rates were applied in 30 different ratios. Growth, color, and density of the turf were estimated and used as the parameters for finding a suitable rate and ratio for these three major nutrients. Color, density, and growth were increased as the rate of N fertilizer increased, but there was no visual response to P or K rates. It is suggested that increases in color, density, and growth were function of N rates, whereas K and P rates maintained the cold hardiness of the turf when high N rates were applied under the conditions of this experiment. Fertility ratio and the rates of 450 kg N/ha, 250 kg K/ha, and 50 kg P/ha were sufficient to prevent dormancy, promote growth, and produce good quality turf throughout the winter. Thus, it is concluded that fertility ratios and rates are the main factors limiting growth and quality of perennial ryegrass in transitional zones similar to Japan.     

Effects of forage type and gibberellic acid on nitrate leaching losses

Nitrogen (N) leaching from soil into water is a significant concern for intensively grazed forage‐based systems because it can cause a decline in water quality and is a risk to human health. Urine patches from grazing animals are the main source of this N. The objective of this study was to quantify the effect that forage type and gibberellic acid (GA) application had on N leaching and herbage N uptake from urine patches on perennial ryegrass–white clover (RGWC), Italian ryegrass and lucerne. A lysimeter study was conducted over 17 months to measure herbage growth, N uptake and N loss to water beneath each of the three forage types with the following treatments: control, urine (700 kg N/ha) and urine with GA (8 g GA active ingredient/ha). Compared with RGWC (205 kg N/ha), N leaching losses were 35.3% lower from Italian ryegrass (133 kg N/ha) and 98.5% higher from lucerne (407 kg N/ha). These differences in leaching loss are likely to be due to winter plant growth and N uptake. During the winter months, Italian ryegrass had higher N uptake, whereas lucerne had lower N uptake, compared with RGWC. The application of GA had no effect on N leaching losses, DM yield or N uptake of forage treated with 700 kg N/ha urine.     

Effect of catch crops on the content of soil mineral nitrogen before and after winter leaching

Since large amounts of nitrogen may be lost by leaching during the winter period, investigations have been carried out to find suitable crops for catching nitrogen during the autumn. The plant species phacelia, common sunflower and italian ryegrass were sown at three times during the late summer. The soil was analysed for mineral nitrogen at the end of November just before incorporation of the catch crops and in the middle of April the following year. The dry matter production and the uptake of nitrogen decreased as the establishment was postponed and the growth period thereby decreased. When sown in the middle of July or at the beginning of August phacelia and italian ryegrass accumulated 150 kg N per ha in the above ground plant parts. The content of soil mineral nitrogen in November was reduced by growing catch crops during the autumn. The content of soil mineral nitrogen increased as the growth period of the catch crops decreased. The content of mineral nitrogen in the upper 50 cm soil layer in April was, irrespective of plant species, increased by catch crops. When no crop was grown the difference between the content of soil mineral nitrogen measured before and after the winter period indicated a net loss of 144 kg of N per ha in 0–100 cm soil depth. When italian ryegrass was sown in the middle of July the previous year the content of soil mineral nitrogen found in April was 59 kg per ha higher compared to the content found in November.     

The response of Stevia (Stevia rebaudiana Bertoni) to nitrogen supply under greenhouse condition

Stevia (Stevia rebaudiana Bertoni) is a perennial plant producing some natural sweeteners. Stevia is considered as a new crop in some countries. This study was conducted to find the stevia response to nitrogen fertilizer supply. Different levels of nitrogen (0, 30, 60, 90, 120, and 150 kg/ha from urea source) were used in a greenhouse condition and then the stevia growth and metabolites were assessed under different availability of nitrogen. Results showed that the optimum growth of stevia was obtained by 60 kg/ha nitrogen and more nitrogen supply did not enhance the stevia growth. It was observed that the total steviol glycosides (SVglys) content of Stevia was significantly increased by nitrogen fertilizer application just up to 30 kg/ha, while it decreased by more rates of nitrogen fertilizer. Our result clearly showed that SVglys yield reached to maximum value by application of 60 kg/ha of nitrogen fertilizer. Since the variation of SVglys content and shoot growth of the stevia were compromised by 60 kg/ha nitrogen, it can be concluded that 60 kg/ha of nitrogen fertilizer could be considered as an optimum rate of nitrogen for stevia and could also be recommended for greenhouse conditions.     

氮磷钾肥对高羊茅生长及抗寒性的影响

利用盆栽试验研究了氮磷钾肥对冷季型草坪草高羊茅生长、叶绿素含量及抗寒性的影响。结果表明,NPK配合施用能有效促进草坪草生长、叶绿素合成及提高抗寒性。NPK处理的叶片数、叶长及株高分别是不施氮处理的1.23、1.73和1.68倍,是不施磷处理的1.96、2.25和2.04倍。播种后100.d,NPK处理SPAD值分别比PK和NK处理高出2.53和3.14倍;越冬期NPK处理的脯氨酸(Pro)、丙二醛(MDA)和电解质渗透率(EL)分别是PK处理的313.6%、36.4%和13.4%,是NK处理的104.2%、14.0%和11.6%。试验结果还表明,磷肥对草坪草生长影响最大,氮肥次之,氮磷肥缺乏均降低草坪草抗寒性;钾肥施用与否对草坪草生长及抗寒性影响不大。说明氮磷钾肥合理施用能有效改善越冬期草坪质量。     

猕猴桃树对氮素吸收、利用和贮存的定量研究

为了探明猕猴桃树对氮素吸收、利用和贮存规律,为确定合理的施肥量和施肥时期提供依据,以10年生秦美猕猴桃树为试材,采用彻底刨根,分解取样的方法,研究了年周期各器官的生物量、氮含量和氮累积量变化动态。结果表明,猕猴桃整株生物量全年增加了12.14 kg/plant,在果实生长期（5月18到9月8日）增加较快,增加量为7.99 kg/plant。氮素在猕猴桃树的根、茎、叶、果及皮层和木质部的分布为:根、叶、果实＞茎;皮层＞木质部;冬季氮的贮存部位是根和茎的皮层,并且主要贮存在茎的皮层。年周期猕猴桃树体总吸氮量为216.78 kg/hm2,进入果实收获期以后和结果前共吸收33.75 kg/hm2,整个果实生长期吸收183.03 kg/hm2,分别占总吸氮量的15.57%和84.43%。5月18日到7月9日和7月9日到9月8日两个阶段吸收的氮素量分别占总吸氮量的53.13％和31.30％,据此计算得猕猴桃的合理施氮量为N 412.91 kg/hm2（产量40 t/hm2);推荐在休眠期结束前施基肥 N 64.29 kg/hm2,座果前追施壮果肥 N 219.38 kg/hm2,果实膨大末期追施促稍肥 N 129.24 kg/hm2。     

不同氮素用量对杭白菊养分累积、转运及产量的影响

通过田间小区试验,研究不同施氮量对杭白菊养分积累、转运及产量的影响,以确定杭白菊最佳氮肥用量。试验设5个处理,氮素用量分别为0、90 kg/hm2、120 kg/hm2、150 kg/hm2、180 kg/hm2,以N0、N1、N2、N3、N4表示,5次重复。结果表明,不同氮素用量影响杭白菊不同时期干物质和养分的阶段积累量,但不影响其积累趋势,整个生育期内杭白菊氮、磷、钾积累量为钾氮磷。不同施氮量影响茎叶氮、磷、钾的转移效率和在不同器官中的分配比率,以不施肥处理最高,N3(150 kg/hm2)次之。在氮、磷、钾三种元素中,转运效率磷氮钾。收获期氮、磷、钾在不同器官的分配比率不同,氮素、钾素分配比率为茎花叶根,磷素分配比率为茎花根叶。各处理杭白菊花的产量在1746.232~211.3 kg/hm2之间,以N3(150 kg/hm2)处理产量最高。在本实验条件下,杭白菊的推荐施氮量为150 kg/hm2。     

不同供磷水平对玉米干物质和磷动态积累及分配的影响

采用田间试验研究了不同供磷水平对玉米干物质和磷动态积累、分配规律及磷肥效率的影响。结果表明,施磷增加玉米茎、叶、穗轴、子粒和整株干重及磷含量,降低磷肥表观利用率、农学效率和生理利用率。随生长推进,不同供磷水平的子粒和整株干重及磷含量不断增加直到成熟,其余器官干重和磷积累峰值出现时间早晚不同;生长后期,子粒成为唯一的库器官,茎、叶、根,甚至穗轴均成为源,有一部分光合产物和磷输出,被重新分配到子粒。出苗后79～100 d,各供磷水平下的子粒干重净增量是相应出苗后58～79 d的0.75～1.02倍;前者子粒磷净增量是相应后者的1.56～2.39倍,说明光合产物和磷向子粒中运输不是同步的过程。同一取样时期,随施磷量增加,各器官的干重和磷含量增加,以施P2O5 90 kg/hm2最好,产量达11231.6 kg/hm2,原因是该处理的玉米穗长、行粒数和单株粒重显著增加,禿尖长度显著减少。     

The Use of Spent Mushroom Substrate (SMS) as an Organic Manure and Plant Substrate Component

The effect of the addition of SMS to soil on the growth of perennial ryegrass was studied in a pot experiment. SMS raised the analyzed levels of P, K, Mg and Electrical Conductivity (EC) but not the level of NO₃-N. At the first harvest, there was a positive response of growth up to a rate equivalent to 50 t/ha but above this growth declined. By the final harvest, there was a positive response of dry matter production up to the highest rate, 400 t/ha. The calculated nitrogen efficiency of dry matter production for SMS averaged 3.1 as against 21.1 for calcium ammonium nitrate. Leaching an SMS/peat column with distilled water at 10 day intervals over a 60 day period recovered 94 percent of the K in the leachate, 33 percent of the P and only 15 percent of the N. In SMS/peat mixes, early growth of tomato seedlings did not respond to rates above five percent of SMS by volume and was reduced when the SMS rate was above 20 percent. When the plants were grown on to a more mature stage, there was a response up to 20 percent SMS. In three experiments, SMS was used as a single nutrient source to supply N, P and K respectively. When used as a source of P and K, there was little benefit from increasing the rate of SMS above five percent. However, when used as a source of N, plant growth increased up to a rate of 25 percent SMS. There was no response to the addition of trace elements to SMS/peat substrates. When an SMS/peat substrate, containing five percent SMS by volume was supplemented with extra N, plant performance was as good as in a peat substrate with inorganic fertilizers.     

氮、磷、钾用量与种植密度对油菜产量和品质的影响

以华油杂9号为试验材料,固定氮（N）:磷（P2O5）:钾（K2O）比例为1:0.55:0.8,设置施纯氮量135、225、315 kg /hm2,以及种植密度15、45、75万株/hm2不同处理,研究施肥量与密度对油菜产量及品质的影响。结果表明,籽粒产量随施肥量、密度的增大而增加,增加施肥量的增产幅度大于增加密度;施肥水平较低时,提高密度的增产作用更为显著。改变施肥量与密度对经济性状、产量构成因素均可产生显著影响,但改变密度对单株有效分枝数及角果数的影响更大。不同肥力下密度每增加30万株/hm2,单株有效分枝数降低1.7～3.8个。主茎籽粒含油量高于分枝,蛋白质及硫苷含量低于分枝。随施肥量增加含油量下降,硫苷、蛋白质含量上升。随密度增加含油量上升,蛋白质含量下降,主茎与分枝的硫苷含量上升,但整株硫苷含量下降。因此,若以减少施肥、节本增效为前提,选择每公顷施纯氮135～225 kg、P2O575～124 kg、K2O 108～180kg,并且在45～75万株/hm2范围内适当提高密度,有利于获得3000kg/hm2以上的籽粒产量。     

钾素营养对玉米生育后期干物质和养分积累与转运的影响

为揭示钾素营养与玉米产量形成的关系,研究了3个施钾水平（K2O　0、113和225 kg/hm2）对玉米生育后期植株不同器官干重及氮、磷、钾积累和转运的影响。结果显示,施钾能显著提高玉米产量。随着施钾量的增加,玉米生育后期干物质积累的最大速率和平均速率提高,最大速率出现时间提前。玉米干物质在各器官中的分配比例随生长发育中心的转移而变化。生育后期干物质和养分由营养体向子粒转运,其中干物质和氮、磷主要来源于穗部营养体的转运,而钾则主要来源于叶片的转运。子粒中氮、磷、钾的积累量分别占总积累量的50.3%～57.1%,59.6%～67.2%和14.0%～33.3%。施钾不但能增加子粒中干物质和氮、磷、钾养分的分配比例,而且还有助于提高干物质和氮、磷、钾养分向子粒转运的转运率。氮的转运率以K1处理最大,为45.7%;干物质、磷和钾的转运率以K2处理最大,分别为7.4%、62.6%和22.4%;子粒养分中54.5%～60.6%的氮,56.0%～85.8%的磷及52.4%～100.0%的钾可以依赖于营养体的转运。     

Yield,forage quality,and nitrogen recovery rates of double‐cropped millet and ryegrass

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.     

不同供氮方式和施氮量对烤烟生长和氮素吸收的影响

2005年5月至9月在云南玉溪采用田间试验和微区试验相结合的方法,研究了传统施肥和优化施肥2个施氮水平对烤烟生长和氮素积累的影响。结果表明,施N.120.kg/hm2的烟株在打顶以后以吸收土壤氮为主;施N52.5.kg/hm2的烟株在团棵期以后以吸收土壤氮为主,该施氮量能够保证烟株从移栽至打顶(即移栽后60.d)阶段的生长需要。但与施N.120.kg/hm2相比,植株氮素营养略有不足,烟株各部位及整株的干物重和氮素积累量略有降低;各时期干物重的分配比例没有区别。另外,打顶期和成熟期,两施氮处理植株所吸收的肥料氮绝对量差异达显著水平,施氮量越高,吸收量也越大。同时,施氮量越多,各个时期各部位和整株中肥料氮的比例越大,且均在团棵期达到最大值;之后呈下降趋势,施氮越多,下降幅度越小。两处理植株都呈现肥料氮比例随叶位上升而减少的规律,施氮量越高,部位间差异越小。     

Comparing cultivars of three cool‐season turf‐grasses for potassium uptake kinetics and potassium recovery in the field

Efficient use of potassium (K) by turf depends on the ability of roots to absorb a high proportion of the fertilizer K applied to the soil. Among turfgrass genotypes, variation in K absorption kinetics of roots and its inheritance is important in the development of genotypes that are more efficient in K absorption from the soil. Therefore, K uptake kinetics of six cultivars each of Kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), and tall fescue (Festuca arundinacea Schreb.) were compared under greenhouse conditions. In 1990 and 1991, field studies of the same cultivars were conducted comparing clipping production rate, leaf blade K concentration, K recovery rate in clippings, K efficiency ratio and visual quality under a moderate K fertilization of 59 kg K/ha/year. Significant differences among species and cultivars were obtained for both absorption kinetics and field recovery of K. Significant correlations between some K uptake parameters and field performance were identified. These results show that genetic differences exist among turfgrasses for K utilization at both the interspecific and intraspecific levels and suggest that a screening program could be developed to identify turfgrass genotypes possessing superior K utilization.     

施钾对青引1号燕麦草产量及根系的影响

在缺钾地区，开展了不同施钾对青引1号燕麦（Avena sativa cv. Qingyin No.1）干物质产量和根系的影响，找出最佳施钾量，为青海省燕麦种子生产提供依据。结果表明，在施N 54.75 kg/hm2和施P2O5 51.75 kg/hm2的基础上，施K2O 40 kg/hm2，青引1号燕麦开花期收获时可获得最高的干物质产量和蛋白产量，分别为29575.0和2099.8 kg/hm2，二者均符合Y=a+bK+cK2函数变化。施K2O 40 kg/hm2，青引1号燕麦株高、总分蘖数、根长和根数最大，分别为184.5 cm、3.22个/株、15.90 cm和26.17 条/株； 施K2O 20 kg/hm2时，植株茎粗和根量达最大，分别为0.585 cm和0.540 g/株。各产量性状、地下生物量以及饲草和蛋白产量间均存在显著或极显著正相关关系。     

水钾一体化对烤烟钾素吸收及生长的影响

【目的】研究负压灌溉下不同施钾模式对烟株生长发育、钾素吸收速率及水肥利用等方面的影响,探索负压灌溉下适合烤烟生长发育的施钾方式及施钾量,为建立作物水肥高效技术提供参考依据。【方法】选用烤烟NC55为供试品种,在温室中进行盆栽试验。采用–15 kPa负压灌溉,施钾方式包括随水施钾 (W) 和钾肥一次性土壤基施 (S) 两种;施钾量以供试地区推荐施钾量 230 kg/hm2为100%,设置该施钾量的100% (K1)、75% (K2) 和50% (K3) 三个水平;以常规灌溉、不施钾肥为CK,共设置SK1、SK2、SK3、WK2、WK3、CK六个处理。测定了烟草农艺性状、干物质积累量、吸钾速率、钾肥利用率、水分利用效率等指标。【结果】团棵期,SK2、SK3的株高、有效叶数、叶长、叶宽、叶面积等农艺性状指标均高于其他处理,但WK2、WK3、SK2、SK3的干物质积累总量分别为31.16 、29.26 、29.92 和28.37g,根干重分别为12.40 、10.51 、11.91 和10.20 g,叶干重分别为17.05 、17.01 、15.67 和16.12 g,均表现为WK2 > SK2,WK3 > SK3;旺长期, WK2的整株重、茎干重及叶干重均大于其他处理,分别为99.18 、19.18 和 61.29 g;成熟期, 烤烟整株重及叶干重均表现出WK2 > WK3 > SK1 > SK2 > SK3,这些处理的整株重依次为139.27 、132.60 、124.50 、117.36 和110.10 g,叶干重依次为 93.97 、87.35 、80.33 、78.56 和 74.80 g;全生育期的水分利用率同样表现为WK2 > WK3 > SK1 > SK2 > SK3,分别为3.78 、3.54 、3.41 、3.28 和 3.22 g/kg,表明随水施钾的水分利用率要明显高于常规土壤施钾,相同施钾方式下烟株水分利用效率随施钾量减少而降低;全生育期的钾肥利用率表现为WK2 > WK3 > SK2 > SK1 > SK3,分别为43.0%、42.6%、21.9%、20.0%和18.5%,其中WK2较SK2,WK3较SK3的钾素吸收量分别增加53.85 kg/hm2、34.65 kg/hm2,表明随水施钾较常规土壤施钾有利于烟草对钾素的吸收;WK2、WK3较SK2分别高出21.1和20.7个百分点,表明负压灌溉下随水施钾能显著提高烤烟的钾肥利用率;随水施钾模式下烟株整个生育期均能维持相对较高的钾素吸收速率,其最大值出现在旺长-平顶期,且显著高于常规土壤施钾。【结论】“水钾一体”施钾模式虽延缓了烟株团棵期长势形成,但促进了烤烟中后期生长发育、干物质积累和烟叶钾素吸收;明显地提高了水分利用效率和钾肥利用率;在烟株全生育期内均维持了较高的钾素吸收速率,尤其中后期钾素吸收速率明显高于常规施钾方式。     

Effect of several production factors on two varieties of rapeseed in the central United States

Two varieties of winter rapeseed (Brassica napus) (Cobra and Liborius) were planted at Brownstown, IL to evaluate the effect of planting date, nitrogen (N) rate, N application timing, and tillage on grain yield and oil content of the grain, grain moisture, plant lodging, winter survival, and plant N content. Results indicated that planting rapeseed approximately one to two weeks prior to winter wheat in this region is preferable to planting earlier. Grain yield showed a significant linear increase with delayed planting date from 25 August to 24 September. Grain yield also increased quadratically with increasing N rate (with an optimum of about 250 kg N/ha) and increased (0.15 Mg/ha) due to splitting the N fertilizer into two even applications. An increase in grain yield was accompanied by an increase in grain moisture with Liborius (late maturing) having significantly greater grain moisture than Cobra. Winter survival increased linearly with delayed planting date but, was accompanied by a significant quadratic increase in plant lodging. Chisel, as compared to disk tillage, increased plant lodging slightly, but decreased winter survival slightly. Neither delayed planting, N rate, nor splitting of spring N affected oil content. Liborius produced significantly more oil than did Cobra.     

追施氮肥量对菘蓝根的外形品质、干物质积累及活性成分含量的影响

采用田间小区试验,设5个处理,氮肥用量分别为 225、 450、 675、 900、 1125 kg/hm2,每一个处理3个重复小区,研究不同追施氮肥量对菘蓝的光合参数、 根的外形品质、 干物质积累及活性成分含量的影响,探讨氮肥施用量对菘蓝植株地上部和地下部生长的生理影响,优选菘蓝最佳追施氮肥量。结果表明, 追施氮肥有利于提高菘蓝叶片的净光合速率、 气孔导度、 胞间CO2浓度、 蒸腾速率,可以显著增加菘蓝根主根直径和根长,有明显的壮根效应;而菘蓝总鲜重随着施氮量提高而增加,但超过 900 kg/hm2 后就不再增加;在450 kg/hm2下菘蓝根侧根数最少,低氮（225 kg/hm2）和高氮（900、 1125 kg/hm2）水平下菘蓝根侧根数增加过多,影响了菘蓝根药材外形品质;随着施氮量增加,地上部和地下部干物质积累先增加后下降,而根冠比不断下降,氮肥量为675 kg/hm2 时地上部干物质积累最大,氮肥量为900 kg/hm2 的地下部干物质积累最大,追施氮肥对地上部的促进效应明显高于地下部。施氮量增加,多糖含量先增加后下降,施氮量为 675 kg/hm2 时菘蓝根中多糖含量最高为158.383 mg/g,而(R,S)-告依春含量没有明显的变化规律,氮肥量为900 kg/hm2 时含量最高达到 0.5655 mg/g。为保证菘蓝根产量和药用品质适宜的追施氮肥量是675900 kg/hm2。     

Response of maize to nitrogen,phosphorus, and potassium fertilizers in the savanna zones of Nigeria

Abstract

Field trials were conducted for three years on the response of maize to nitrogen (N), phosphorus (P), and potassium (K) fertilizers on Oyo Soil Series (Arenic Haplustalf) and Iregun series (Aquic Haplustalf) in the derived savanna and southern guinea savanna zones of Nigeria, respectively. Nitrogen fertilizer as granulated urea at rates 0–300 kg N/ha, P fertilizer as single superphosphate at rates 0–120 kg P/h, and K fertilizer as muriate of potash at rates 0–180 kg K/ha were used for the different nutrient combinations. The base rates for N, P, and K were 100 kg N/ha, 40 kg P/ha, and 60 kg K/ha, respectively. The results of the trials showed that annual application of the blanket recommended N, P, and K rates to maize grown under intensive land use system could not produce optimum yield. Fertilizer efficiency varied along with soil test values from year to year. The highest response by maize in these zones was to N, the optimum rate ranged from 50–100 kg N/ha. Application of high rates of P and K fertilizers on soils with fairly sufficient nutrient level showed no significant effect on maize yield. But when P and K were applied at low rates (20 kg P/ha and 30 kg K/ha), their contents in the leaf and maize yield, in most cases, increased significantly. The results, however, showed that N, P, and K recommendations for optimum maize yield in both zones are 50–100 kg N/ha, 20 kg P/ha, and 0–30 kg K/ha, respectively.     

Vegetative responses of silage cats fertilized in the growth chamber with various levels of N and K

Oats (Avena sativa L.) are often harvested for silage in the Great Lakes states. The objective of this research was to obtain additional information on the response of oats to N and K fertilization. ‘Froker’ spring oats were grown from seed under 27 C day/21 C night temperatures in a growth chamber. The soil was a 4:1 mixture of Dodge silt loam soil (Typic Argiudoll) and sand that contained low levels of N and K. The potted plants were fertilized with 0, 50, 100, and 200 kg/ha of N as NH₄NO₃ in all combinations with 0, 200, and 400 kg/ha of K as KC1. Plants were harvested at early inflorescence emergence (43 days after seeding). Fertilization with N significantly increased the dry matter yields (g/pot) of the herbage and total plant, the number of axillary tillers/pot, and herbage N percentage. Root yields were increased only with the first increment of N. Nitrogen fertilization had no significant effect on height of the primary shoots and herbage K percentage. The first increment of K (200 kg K/ha) significantly increased herbage and total plant dry matter yields, while the second increment (400 kg K/ha) gave no further yield increases. However, number of axillary tillers/pot and herbage K percentage were increased significantly with each higher K rate. Potassium fertilization had no significant effect on root yield, primary shoot height, and herbage N percentage. It was concluded that the vegetative growth of oats is very responsive to N fertilization to the highest rate applied (200 kg N/ha), but responds only to the first increment of K (200 kg K/ha).