Effect Of Potassium Fertilization Research Articles

Nutrient demand of stone fruits

Effects of nitrogen, phosphorus and potassium fertilization were investigated on the change of nutrient content, vegetative and generative production of apricot, peach and sour cherry trees, as well as on frost hardiness in long term experiments. Nitrogen and phosphorus fertilization increased only the concentration of these elements in cherry leaves without effect on growth and yield. Consequent potassium effect was proved on these stone fruit species. Effect on yield appeared following the first higher crop load.
 Potassium supply has positive effect on frost hardiness of apricot and sour cherry flowers and peach flower buds.
 In peach, the lime content of soil decreased the yield but it could be compensated by potassium dressing to some extent. Favourable nutrient boundary values were determined for soil and foliage.

Adubação com potássio e nitrogênio em três cíclos de produção da bananeira cv. prata-anã

O nitrogênio, depois do potássio, é o elemento mais exigido pela bananeira. O desbalanço entre N e K afeta a produção e a qualidade do fruto de banana. O objetivo deste trabalho foi avaliar a influência das adubações com nitrogênio e potássio na produção da bananeira c.v. Prata-Anã (grupo genômico AAB). O experimento foi realizado em Latossolo Vermelho-Amarelo na região do Semi-árido do Norte de Minas Gerais e irrigado por microaspersão. Estudaram-se cinco doses de N (0; 200; 400; 800 e 1600 kg ha-1ano-1) e cinco doses de K2O (0; 200; 400; 800 e 1600 kg ha-1ano-1), em esquema fatorial (5x5), durante o 2º, 3º e 4º ciclos de produção. A aplicação de doses crescentes de N elevou o teor de Mn nas folhas acima da faixa adequada, promovendo queda na produção de banana no 2º e 3º ciclos. Portanto, infere-se que o teor de Mn nas folhas atingiu nível tóxico. Houve efeito do K sobre a produção de banana apenas no 4º ciclo. A produção máxima de banana no 4º ciclo foi obtida com a aplicação de 962,5 kg de K2O ha-1ano-1. Não ocorreu interação significativa entre N e K.

Uptake of Nitrogen, Phosphorus, and Potassium by Mat Rush and Effects of Nitrogen and Potassium Fertilizers on Plant Yield and Quality in Paddy Field Soil

Uptake of nitrogen (N), phosphorus (P), and potassium (K) by Mat Rush (Juncus effusus L. var. Decipiens Bchen) (cv. Gangshan 3) and the effects of N and K fertilizers on yield and quality of paddy field‐grown Mat Rush were studied. The results showed that plant tissue N and K concentrations gradually declined with plant growth, ranging from the maximum of 3.32% and 3.48% to the minimum of 1.66% and 1.79%, respectively. Plant tissue P concentration declined slightly during early growth, then increased in effective‐stem tillering stage. Highest P concentration was 0.36%. Maximum accumulations of N, P, and K in foliage were N 293.9 kg ha−1, P2O5 59.7 kg ha−1, and K2O 374.5 kg ha−1, respectively. In comparison with the control, N fertilizer significantly increased stems per hill (SPH), average stem length (ASL), long stem percentage (LSP), and stem chlorophyll content (SCC), beneficial to stem quality improvement, leading to significantly increased yield, and meanwhile caused higher stem flowering rate (SFR) which would deteriorate the stem quality. There was no significant difference in stem yield and quality between N1 (450 kg ha−1) and N2 (900 kg ha−1). Potassium fertilizer significantly improved all quality parameters and yield, except for SFR. Rates of 450 kg ha−1 of N fertilizer and equal amounts of K fertilizer applied to paddy fields appear optimum to obtain high yield and quality in Mat Rush production.

Participatory conservation tillage research: an experience with minimum tillage on an Ethiopian highland Vertisol

Farmer participatory tillage trials were conducted in a highland Vertisol area of Ethiopia during the 1999 and 2000 cropping seasons. This participatory initiative clearly demonstrated that incorporating farmers’ knowledge, ideas and preferences could improve the wheat production package. A traditional practice of Chefe Donsa farmers—applying ash from their homesteads to their fields to enable early-sown crops to withstand frost—led to the verification of the yield-enhancing effect of inorganic potassium fertilizer on wheat. Farmer adoption of a minimum tillage production system increased the gross margin of wheat production by US$ 132 per hectare—based on 1999 prices—relative to the traditional flat seedbed system. The minimum tillage system was characterized by a much lower level of soil manipulation relative to the traditional flat seedbed system, and, as a consequence, markedly reduced the total human labor and draft oxen requirements for wheat production. Thus, the minimum tillage system could be an effective intervention for soil conservation due to early-season vegetative cover of the soil surface. Also, the early crop harvest associated with the minimum tillage system was highly beneficial for small-holder farmers—since the early harvest coincided with the cyclical period of severe household food deficits and high grain prices in local markets.

Atributos químicos do solo afetado pelo manejo da água e do fertilizante potássico na cultura de arroz irrigado

O desenvolvimento das culturas nas várzeas é extremamente influenciado pelo manejo destas, devido aos atributos químicos e físico-hídricos que elas possuem. O decréscimo na produtividade, verificado no monocultivo contínuo de arroz (Oryza sativa L.) irrigado, pode estar relacionado à redução na fertilidade do solo, em decorrência da lixiviação de nutrientes. Com o objetivo de se avaliar os efeitos de manejo da água (MA1 - inundação contínua e MA2 - inundação intermitente seguida de contínua) e do fertilizante potássico (K1 - na semeadura; K2 - adubação parcelada e K3 - meia dosagem parcelada) na cultura de arroz irrigado sobre alguns atributos químicos de um solo Gley Pouco Húmico, foram conduzidos experimentos durante três anos consecutivos. Na inundação contínua ocorre maior lixiviação de cálcio e de potássio, teor de fósforo no solo e saturação por alumínio e menor pH na camada superficial do solo em relação à inundação intermitente, além de aumento do teor de potássio e do pH e diminuição de saturação por alumínio em profundidade. A inundação intermitente e o parcelamento do potássio podem contribuir na redução das perdas de nutrientes em solos de várzea que apresentam percolação excessiva. Alguns atributos químicos do solo podem ser melhorados através do manejo adequado da cultura do arroz irrigado, envolvendo manejo da água e do fertilizante potássico.

Efeito de doses de NPK sobre os teores de nutrientes nas folhas e no solo, e na produtividade do maracujazeiro amarelo

Objetivou-se avaliar a influência das adubações com nitrogênio, fósforo e potássio nos teores de nutrientes das folhas do maracujazeiro amarelo (Passiflora edulis f. flavicarpa Deg.) e em propriedades químicas do solo, tendo em vista maximizar a produtividade e otimizar a prática da adubação. O experimento foi conduzido no período de maio/96 a abril/98, em Latossolo Amarelo do Município de Cruz das Almas (BA). Empregou-se o delineamento experimental de blocos casualizados, em esquema fatorial fracionado ½ de 4³, com dois blocos incompletos, avaliando-se quatro doses de N (0, 100, 200 e 300 kg ha-1 ano-1), de P2O5 (0, 80, 160 e 240 kg ha-1 ano-1) e de K2O (100, 300, 500 e 700 kg ha-1 ano-1). Amostragens de solo e folhas foram realizadas aos 12 e 24 meses após o plantio, bem como foi avaliada a produtividade no primeiro e no segundo ano. A adubação nitrogenada não influenciou os teores de N na folha, mas diminuiu os de boro e reduziu o pH do solo no segundo ano de cultivo. A adubação fosfatada aumentou, em média, apenas 12% os teores de P nas folhas e 35 vezes no solo. A adubação potássica elevou os teores do nutriente nas folhas do maracujazeiro, e no solo a valores acima do nível ótimo. A produtividade máxima de 22,1 t ha-1, em dois anos de cultivo, foi obtida com a aplicação de 244 kg de N, 72 kg de P2O5 e 285 kg ha-1 de K2O.

Effect of potassium fertilization on its available and fixed content in vineyard soil

The experiment was conducted on brown forest soil in the vineyard with Sauvignon blanc variety on Kober 5BB rootstock. During a thre- year experiment (1994-1996), potassium fertilizer was added in a dose of 0 kg K2O/ha, 50 kg K2O/ha, 100 kg K2O/ha, 150 K2O/ha respectively. After the determination of soil potassium content (1870-1920 mg K2O/100 g), its available form was monitored by using two different extraction methods (AL method and 1N ammonium-acetate extraction). The amount of extracted available K was not significant between the used methods, while the effect of fertilization was visible only at 150 kg/ha potassium rate during the first year in soil layers (30-60 cm, 60-90 cm). Also, another examined soil K fraction (fixed K+) was not affected by K fertilizer application.

Effect of foliar and soil potassium fertilisation on wheat yield and severity of Septoria tritici blotch

Field research was undertaken to investigate the effects of potassium K2SO4 (36% K) as a foliar spray and/or soil application on grain yield, 1000-grain weight and severity of Septoria tritici blotch on wheat during 1998 and 1999. Two Syrian bread wheat cultivais (Bohuth 6 and Cham 6) and one promising mutant line (L92-6) were used in this study. Six treatments were evaluated: untreated (without K application), 3 and 5 g/L foliar K application, 60 kg/ha soil K application, 3 g/L foliar K + 60 kg/ha soil K application and 5 g/L foliar K + 60 kg/ha soil K application. Plants were sprayed with 2 L/m2 K2SO4 solution three times at 5-day intervals stalling at growth stage (GS) 32, and thereafter inoculated with a mixture of 15 virulent isolates of Septoria tritici at GS 33–34. The results showed that the average response to application of potassium fertilisers was positively correlated (r=0.94) with the susceptibility level of cultivais compared with the control. The level of infection for all potassium treatments was reduced by 48%, 28% and about 0% in 1998 and by 47%, 35% and 21 % in 1999 for Bohuth 6, L92-6 and Cham 6, respectively. Mean increments for grain yield ranged from 34-120% in 1998, and 80-170% in 1999 for the 5 g/L foliar K + 60 kg/ha soil K application. This combined treatment appealed to be more effective on calcareous soils, which aie typical of Mediterranean environments.

Avaliação da infestação de insetos-praga associados à batata (Solanum tuberosum L.) sob efeito de nutrientes nitrogenados e potássicos e teores acumulados de aminoácidos livres nas cultivares Achat e Monalisa

Evaluation of insect-pest infestation associated to potato (Solanum tuberosum L.) under effect of nitrogen and potassium fertilizers and the accumulated amount of free aminoacids in Achat and Monalisa cultivars. The objective of this work was to evaluate the occurence of insect-pests on potato plants influenced by dosages of nitrogen and potassium accumulated in plant organs. A total of 169 plants of the Achat and Monalisa cultivars were evaluated to determine the presence-absence of Diabrotica speciosa Germar, 1824 and Agrotis ipsilon Hufnagel, 1767. The experiment was carried out and executed at the Universidade Federal Fluminense, and the delineation was complete randomized block design, with four replication and nine treatments, using three fertilization level (0; 75 and 150 Kg/ha) with N-urea + KCl. The aminoacid levels were adjusted by the Leucine standard-curve (µg/l), using the Ninhydrin method, at 570 nm. The results showed that the tubercles of Monalisa accumulated high free aminoacid levels with 7,95% in the treatment N1K2 and 7,75% in the N2K1.These treatments, induced the infestation by D. speciosa larvae in 27,03%, when the aminoacid level was 2,01 ± 0,58% (X ± EP), with probability of 0,0196<P<0,05. The studied cultivars showed a diferential behavior, especially, in relationship to the N and K metabolism, resulting in the accumulation of free aminoacids, and consequently in the pest infestation increment. The results indicated that the aminoacid level increasing affects the tubercles production, mainly in the Monalisa cultivar, in winter cropping with long dry periods.

Response of radish to varying levels of irrigation water and fertilizer potassium on clay terrace soil of Bangladesh

A field experiment was conducted in the rabi (dry) season of 1998–99 on a clay terrace soil of Bangladesh, in order to study the effects of irrigation and potassium (K) fertilization on the yield, total water use, and water use efficiency of radish. Both irrigation and K application were found to be indispensable for increasing the yield of radish, due to their individually significant impact on the yield. The interaction effect of irrigation and K application was insignificant, but the highest yield of 30.1 Mg ha−1 was obtained under the highest levels of irrigation and K application (four irrigations with 160 kg K2O ha−1) as the positive effects of both treatments on the radish yield. From the economic viewpoint, the yield of 29.9 Mg ha−1 under four irrigation levels with 120 kg K2O ha−1 gave the highest net benefit. The total water use in this case was 101 mm, having the water use efficiency 297 kg ha−1 mm−1. Based on the acceptable economic yield, high water use efficiency, and the maintenance of proper soil fertility, four irrigation levels and K application at the level of 120 kg K2O ha−1 proved to be the best combination for the sustainable radish cultivation in Shallow Red–Brown Terrace Soil of Bangladesh.

TEORES DE NUTRIENTES FOLIARES NO MARACUJAZEIRO-AMARELO ASSOCIADOS À ESTAÇÃO FENOLÓGICA, ADUBAÇÃO POTÁSSICA E LÂMINAS DE IRRIGAÇÃO

Conduziu-se um experimento em Campos dos Goytacazes-RJ, para avaliar o efeito da adubação potássica, de lâminas de irrigação e de épocas do ano nos teores de N, P, K, Ca, Mg, S, Zn, Fe, Cu, B, Cl, Mn e Na no maracujazeiro-amarelo (Passiflora edulis f. flavicarpa). Foram testadas, num Argissolo Amarelo distrófico, quatro doses de potássio (76; 307; 531 e 764 g planta-1 ano-1 de K), utilizando o cloreto de potássio, sob seis lâminas de irrigação (0; 25; 50; 75; 100 e 125% da ETo - Evapotranspiração de referência), num esquema fatorial 4 x 6. Os teores de nutrientes, na matéria seca foliar, relacionados com a máxima produtividade de frutos (43,5 t ha-1), variaram, nas diferentes épocas do ano, de 34,7 a 49,8 g kg-1 de N, 2,31 a 3,43 g kg-1 de P, 23,5 a 35,5 g kg-1 de K, 10,6 a 15,1 g kg-1 de Ca, 2,13 a 3,62 g kg-1 de Mg, 3,19 a 4,33 g kg-1 de S, 16,9 a 28,9 g kg-1 de Cl, 77 a 135 mg kg-1 de Fe, 50,1 a 91,4 mg kg-1 de Mn, 26,1 a 37,6 mg kg-1 de Zn, 4,53 a 95,4 mg kg-1 de Cu, 22,8 a 54,5 mg kg-1 de B e de 0,96 a 2,31 g kg-1 de Na. O adubo potássico elevou os teores de K e Cl e reduziu os de Mg, Mn, Zn e Na nas folhas do maracujazeiro. A irrigação afetou os teores de N, Cl e Na e não influenciou nos teores foliares dos demais nutrientes avaliados.

Responses of potato (Solanum tuberosum) to potassium fertilizers

Between 1989 and 1999, 33 experiments tested the effects of potassium (K) fertilizer on the yield and quality of potatoes. The experiments were done on a range of soil types and used varieties and management conditions common to modern commercial production. The average yield in these experiments was 48 t/ha. Nearly half of the experiments were done on soils that had exchangeable K values &lt; 120 mg/l (MAFF Indices 0–1) but use of K fertilizer resulted in statistically significant increases in fresh weight yield in only seven experiments. Generally, soil exchangeable K was a poor predictor of the probability of a yield response. Potassium fertilizer caused an increase in dry weight yield in only four experiments and these experiments were characterized by the absence of irrigation, soils with small amounts of exchangeable K and use of determinate varieties. Re-examination of published data supported the findings in the current work: potatoes are not particularly responsive to K fertilizer and the optimal K application rate is rarely &gt; 170–210 kg K/ha. When applied at the optimal rate, the effects of K fertilizer on tuber dry matter concentration were nonsignificant. Exceeding the optimal K application rate caused occasional reductions in tuber dry matter concentrations particularly if potassium chloride (KCl) was used. In the two experiments where it was tested, application rate and form of K had no effect on crisp fry-colour. The effect of K fertilizer on tuber K concentration was measured in 21 experiments and on average each tonne of fresh weight yield was associated with 4·2 kg K. The range in values was large, 2·8–5·7 and related to soil exchangeable K.For fertilizer recommendations based solely on the probability of a significant yield response to K fertilizer it is suggested that no more than 210 kg K/ha be applied even on soils with &lt; 120 mg exchangeable K/l. For fertilizer recommendations based on crop K removal, an uptake value of 4·8 kg K/t fresh weight (FW), as has been suggested, would be adequate, although errors in the estimation of yield may lead to over or under application of K. Since there was little evidence to support fertilizer policies that apply more K than is removed by the crop a fertilizer recommendation system based primarily on the probability of a yield response would be more than sufficient.

ANNUAL APPLICATIONS OF N, P, AND K INTERRUPT ALTERNATE-YEAR NUT CROPS IN BLACK WALNUT

Nut production and diameter growth at breast height of black walnut (Juglans nigra L.) were measured for 5 years to determine the effect of nitrogen (N) and potassium (K) fertilization separately, in combination, and with and without phosphorus (P) broadcast annually for 4 years at two rates. Fertilization significantly (P>0.05) increased nut production and diameter growth. Treatments containing P with N and/or K were most effective for increasing nut production, and treatments containing N were most effective for increasing diameter growth. Doubling the rate of application did not cause a corresponding increase in nut production or diameter growth. Leaf levels of N, P, and K were within the adequate range, and the addition of N increased leaf N, but not P and K. The alternate bearing tendency that was present in year 3 of the study was not apparent in years 4 and 5.

Potassium Fertilization Effects on Alfalfa in a Mediterranean Climate

Potassium fertilization rates for alfalfa (Medicago sativa L.) have been increasing with intensive cropping systems or decreasing with policies that generally lead to reduced fertilizer inputs. In this case, nutrient buildup or maintenance of high soil test levels may not be desirable and drawdown of K reserves may be beneficial in the short term. The objective of this research was to evaluate the effects of potassium fertilization of alfalfa in areas of high soil exchangeable K levels and long growing seasons. A field experiment was established under irrigation from 1993 to 1997 in the Mediterranean environment of the Ebro Valley (Spain) on a silty clay loam soil. The treatments were five annual rates of K (0, 41.5, 83, 166, and 332 kg K ha−1) and two rates of K (166 and 332 kg K ha−1) applied prior to seeding on two alfalfa cultivars. The average annual dry matter (DM) yield was 21.5 Mg ha−1 and showed a small linear response to K fertilization (Pr &gt; F = 0.0589). Total K removal in the herbage increased linearly with each rate of K and reached 1728 kg K ha−1 with the application of 332 kg K ha−1 yr−1, compared with 1546 kg K ha−1 without K fertilization. At the end of the experiment, soil ammonium acetate extractable K (Ke) increased little with K rates, and the differences were observed only in the first 30 cm of depth. Despite the uptake of 1546 kg K ha−1, soil Ke values did not change appreciably, suggesting that much of the K uptake was derived from the fertilizer and from nonexchangeable soil K fractions. Although K fertilization slightly increased alfalfa DM yields in this high testing Mediterranean soil, the economic benefit of this limited response does not justify the expense.

Produtividade e valor nutritivo do capim-elefante cv. Napier sob doses crescentes de nitrogênio e potássio

Avaliaram-se os efeitos das adubações nitrogenada e potássica sobre o capim-elefante "Napier". Quatorze combinações entre N e K, de um fatorial incompleto de N e K, avaliados em sete doses de N (20, 50, 100, 200, 300, 350 e 380 kg/ha de N) e sete de K (16, 40, 80, 160, 240, 280 e 304 kg/ha de K), foram obtidas de acordo com a matriz Box Berard aumentada 3, com acréscimo de um ponto. Os tratamentos foram distribuídos em blocos ao acaso com três repetições. A produtividade foi aumentada pelas adubações nitrogenada e potássica em 86%. A relação lâmina/colmo e o teor de Mg2+ diminuíram com a adubação potássica. Os teores de P e Ca2+ diminuíram com a adubação nitrogenada, enquanto o teor de proteína bruta aumentou de maneira quadrática pelas adubações nitrogenada e potássica. O teor de K aumentou com a adubação potássica e diminuiu com a nitrogenada. O nível crítico de potássio na planta foi 1,85 dag/kg na matéria seca.

Effect of Soil Moisture and Potassium Fertilizer on Shoot Water Potential, Photosynthesis and Partitioning of Carbon in Mungbean and Cowpea

The effect of different rates of potassium (K+) on shoot water potential, photosynthesis and carbon movement (using 14C) at the V3/4 growth stages was studied in mungbean (Vigna radiata L. Wilczek), a drought‐susceptible legume, and cowpea (Vigna unguiculata L. Walp), a drought‐tolerant legume, grown under low‐ and high‐irrigation regimes under controlled conditions. Soil moisture and K+ affected all measured parameters in the two species. The rate of photosynthesis was higher at reduced water stress when K+ was applied. The impact was greater in cowpea, which had an inherently high rate of carbon assimilation. Mungbean and to a lesser extent cowpea allocated greater quantities of carbon to roots under dry conditions, especially with added K+. The distribution of 14C into other plant parts was also increased at higher rates of K+ application under both soil moisture regimes. Thus, application of K+ seems to have a beneficial effect in overcoming soil moisture stress and increasing physiological parameters and carbon partitioning in these two important tropical food legumes.

Effect of potassium fertilizer on the yield, quality and potassium offtake of sugar beet crops grown on soils of different potassium status

The effect of different rates of potassium (K) fertilizer on the yield and quality of sugar beet was studied in a series of 26 trials on soils of different type and K index between 1992 and 1997. There were few yield responses even though the majority of trials were on soils of low K index, and large quantities of fertilizer were applied (0–600 kg K/ha). Potassium offtakes (kg/ha) in the harvested beet increased asymptotically, not linearly, with yield and were much larger for a given yield on high K index soils than on low index soils. Commercially acceptable concentrations of beet K for processing are in the range 700 to 1000 mg K/100 g sugar. Concentrations in excess of this decrease the amount of sugar crystallized from the extracted juice. They were not greatly affected by large applications of fertilizer K but were strongly influenced by long-established differences in soil exchangeable K (Kex) due to soil type, previous cropping or manuring history.The asymptotic nature of the K offtake[ratio ]yield relationship was confirmed by factory tarehouse measurements relating to the national sugar beet crop delivered during the 1993–97 UK processing campaigns. Potassium offtakes generally increased linearly with yield up to 60–70 adjusted t of clean beet/ha, but increased little beyond that. The amount of K removed by a 60–70 t/ha crop of beet varied from 70 kg K/ha on low K index sandy loams to 120 kg K/ha on clay soils of K index 3 and above. Further increases in yield decreased the amount of K in fresh beet from 1·7 to 1·4 kg K/t on low K index soils, and from 3·6 to 2·5 kg K/t on high K index soils.An analysis of data from individual fields of commercially grown sugar beet showed that much of the site and season variation in the K content of beet was due to differences in K uptake driven by Kex, and to differential effects of nitrogen (N) supply on K uptake and sugar yield. Regressions on Kex and total crop N (kg/ha) accounted for c. 30 and 50% of the variance in beet K content, respectively, and the two together for over 60%. Total N uptake by the crops ranged from 100 to 550 kg N/ha. The total K content of the crop and the amounts of K in the beet (kg/ha) both increased linearly with crop N over the whole of this range, whereas sugar yield increased asymptotically with total uptakes of N up to 250–300 kg N/ha. Consequently, low yielding crops grown on soils in which N and K were freely available produced beet of poor K quality. However, the asymptotic relationship between beet K (kg/ha) and yield implies that, in many situations, the processing quality of the beet could be improved by increasing yield through better agronomy.

Effect of Nitrogen and Potassium Fertilizers on Root Growth of Sweet Potato Intercropped with Maize

Effect of Nitrogen and Potassium Fertilizers on Root Growth of Sweet Potato Intercropped with Maize

The effects of sodium and potassium fertilizers on the grazing behaviour of dairy cows

Sodium fertilizer has been observed to increase the grazing time of dairy cows kept on pastures of restricted availability, but it is unclear whether this is a behavioural response to changes in pasture composition or whether it is an indirect effect of a reduction in herbage availability caused by increased cow production and appetite. Sodium fertilizer was applied in an experiment utilising tall pasture and low stocking rates so that availability would not be restricted. Cows on the pasture with sodium fertilizer still had longer grazing times than those on pasture where no sodium fertilizer had been applied. They had more feeding bouts but bout length was reduced, and they had faster biting and walking rates while grazing. They ruminated for longer, with a faster chewing rate, and spent longer standing idle and less time lying idle. They had longer drinking bouts but a similar number of them, compared to the cows on pasture without sodium. The fixed and variable energy costs of grazing and drinking bouts were estimated, these being the energy requirements for activities that are independent and dependent of bout duration, respectively. It is proposed that for grazing bouts the low ratio of fixed costs (getting up and lying down) to variable costs (standing and walking) favoured an increase in bout number to increase the grazing time of cows grazing pasture fertilised with sodium. For drinking bouts, the high ratio of fixed costs (getting up, lying down, standing and walking to the trough) to variable costs (standing at the trough) favoured bout elongation to increase the drinking time of cows grazing pasture fertilised with sodium. A second experiment with unrestricted herbage availability between morning and afternoon milking compared the grazing response to sodium and potassium fertilizers with a control where no fertilizer was applied. Grazing time was increased most by sodium and a smaller response occurred with potassium. The proportion of herbage that was rejected by the cows decreased with sodium and to a lesser extent potassium. It is concluded that changes in herbage composition with sodium fertilizer increase feeding and drinking by the grazing dairy cow, with the increase in feeding being achieved by increased bout number but reduced bout length, and the increase in drinking being by increased bout length.

Effect of peat ash fertilization on the nutrient status and biomass production of short-rotation willow on cut-away peatland area

Recycling of peat ash back to cut-away peatland areas for growing short-rotation willows was studied in a field experiment in central Finland. Application amounts of 10, 160, 320 and 640 t/ha were tested. Willow ( S. x dasyclados) planted as cuttings was grown with one-year rotations for four years. The effect of additional fertilization (0, N, P, K, NP, NK, PK, NPK) was also tested. Biomass production, soil and foliar nutrient concentrations were measured. High ash application amounts increased the soil extractable P, K, Ca, Mg and Fe concentrations manyfold compared with the 10 t/ha treatment. Marked increases were also noted in soil pH, electrical conductivity and microbial activity. At the 10 t/ha treatment foliar K concentrations were low and higher applications of ash or additional K fertilization increased foliar K concentrations. The effect of potassium fertilization on foliar K concentrations decreased with increasing amounts of ash used. Biomass production was low at the 10 t/ha treatment and increased manyfold with higher application amounts. However, additional potassium fertilization was necessary unless extremely high application amounts were used. Even the highest application amount of peat ash (640 t/ha) was not toxic to the willow.