Potassium-releasing power of soils from the Agdell rotation experiment assessed by glasshouse cropping

1961 ◽  
Vol 57 (3) ◽  
pp. 381-386 ◽  
Author(s):  
P. W. Arnold ◽  
B. M. Close

1. On cropping Agdell Experiment topsoils to exhaustion with perennial rye-grass in the glasshouse the total K uptakes were directly proportional to the initial exchangeable K contents of the soils.2. The ability of the Agdell topsoils to release non-exchangeable K under glasshouse conditions decreased in the order: PK-rotation with fallow < NPK rotation with fallow < PK-rotation with clover < NPK-rotation with clover < no-fertilizerrotation with fallow = no-fertilizer rotation with clover.3. Releases of non-exchangeable K were at least 2·5 times larger than the falls in the exchangeable K for all the Agdell soils.4. In a ‘take-down’ experiment in the glasshouse on a soil receiving K fertilizer each year in the Saxmundham Rotation I Experiment, loosely held non-exchangeable K was released at a near-linear rate. At least a part of the loosely held non-exchangeable K in the Agdell soils was also released at a near-linear rate.

2001 ◽  
Vol 137 (2) ◽  
pp. 195-203 ◽  
Author(s):  
T. R. RUPA ◽  
S. SRIVASTAVA ◽  
A. SWARUP ◽  
D. SINGH

The effect of 27 years of continuous cropping, fertilization and manuring on potassium (K) supplying capacity of a Typic Ustochrept soil profile from Delhi, India under a maize–wheat–cowpea (fodder) cropping system was investigated by employing the quantity/intensity (Q/I) approach. The predominant mineral suite of the <2 μm clay fraction was illite. The values of equilibrium activity ratio of K in solution in equilibrium with the soil (ARKE), labile pools of K (KL), immediately available K (ΔK0), K available with difficulty (KX) and water soluble+exchangeable K (1 M NH4OAc K) in different soil layers (0 to 105 cm) under different treatments were in the following order: 100% nitrogen, phosphorus and potassium (NPK)+farmyard manure (FYM) > 100% NPK > control (no fertilizer) > 100% N >100% NP. The ARKE value, a measure of availability or intensity of labile K in soil decreased with profile depth due to greater K fixation by specific sites in the lower layers. The quantity of specifically sorbed K (KX) and the potential buffering capacity of soil (PBCK) showed a increasing trend with soil depth. In soil without K fertilizer treatments (control, 100% N and 100% NP) about 100% of the total K uptake by crops was from non-exchangeable soil K reserve as compared to 49·5 and 32·2% when annually 84 kg K/ha and 84 kg K/ha+FYM at the rate of 15 t/ha were applied. The results showed the greatest depletion of non-exchangeable K reserves in the plots which did not receive K fertilization. To ensure sustained crop production under intensive cropping, application of recommended dose of NPK plus FYM is required.


1975 ◽  
Vol 84 (3) ◽  
pp. 513-524 ◽  
Author(s):  
T. M. Addiscott ◽  
A. E. Johnston

SUMMARYSoils from long-term experiments at Rothamsted and Woburn were cropped for very long periods (up to 5½ years) with ryegrass in pots. Measurements of the potassium taken up by the ryegrass that was not exchangeable to ammonium acetate and the kinetics of its release both suggested two categories of non-exchangeable K. Of these, the first to be released was closely related to the initial exchangeable K, whilst the second, though partly related to the initial exchangeable K was also influenced by the clay percentage. Release of both categories may have been controlled by diffusion, because both showed good relationships between the quantity released and time. It is suggested that the first category may be K ‘trapped’ when K fertilizer added in the field decreased the interlamellar spaces of vermiculite layers in clay particles, whilst the second may simply be the ‘native’ K (described by others) present in clay and other minerals in the soil.Resowing the soils (without drying them) during the later stages of K. uptake suggested that the ability of the old ryegrass to absorb K was not a factor limiting K uptake even after long growth.When the ryegrass ceased to grow, the mean K potentials in the exhausted soils were close to the ‘uptake potential’ for ryegrass derived earlier by considering K uptakes from soils in relation to the quantity/potential relationships of the soils. Drying and rewetting the exhausted soils released K; the amount was influenced in one group of soils by the exchangeable K in the moist exhausted soil and in another group by the clay percentage.


Author(s):  
Ciro A. Rosolem ◽  
Antonio P. Mallarino ◽  
Thiago A. R. Nogueira

AbstractPotassium (K) is found in plants as a free ion or in weak complexes. It is easily released from living or decomposing tissues, and it should be considered in fertilization programs. Several factors affect K cycling in agroecosystems, including soil and fertilizer K contributions, plant K content and exports, mineralization rates from residues, soil chemical reactions, rainfall, and time. Soil K+ ions can be leached, remain as exchangeable K, or migrate to non-exchangeable forms. Crop rotations that include vigorous, deep-rooted cover crops capable of exploring non-exchangeable K in soil are an effective strategy for recycling K and can prevent leaching below the rooting zone in light-textured soils. The amount of K released by cover crops depends on biomass production. Potassium recycled with non-harvested components of crops also varies greatly. Research with maize, soybean, and wheat has shown that 50–60% of K accumulated in vegetative tissues is released within 40–45 days. A better understanding of K cycling would greatly improve the efficacy of K management for crop production. When studying K cycling in agricultural systems, it is important to consider: (1) K addition from fertilizers and organic amendments; (2) K left in residues; (3) K partitioning differences among species; (4) soil texture; (5) soil pools that act as temporary sources or sinks for K. In this chapter, the role of cash and cover crops and organic residues on K cycling are explored to better understand how these factors could be integrated into making K fertilizer recommendations.


1979 ◽  
Vol 92 (3) ◽  
pp. 695-702 ◽  
Author(s):  
J. McEwen ◽  
A. E. Johnston

SUMMARYA small-plot experiment on sandy loam soil at Woburn tested the effects of subsoiling by hand and of incorporating a large dressing of P and K fertilizer into the subsoil.Ths treatments were applied once in 1973 and their effects were assessed from 1974 to 1977 on the yields of, and N, P, K uptakes by, barley, potatoes, wheat and sugar beet grown in rotation. All crops were present each year and all plots received annual seedbed dressings of N, P and K appropriate to the crop. Dolomitic limestone was applied once in the rotation. The effects of the treatments on P soluble in 0·5 M-NaHCO3 and exchangeable K in surface and subsoils were measured.Subsoiling alone increased the 4-year mean yield of wheat by 21%, of barley by 24% and of sugar from sugar beet by 11%. Mean yield of potatoes was unaffected.Incorporating P and K into the subsoil increased the mean yield of potatoes by 16% and further increased mean yield, in addition to the effect of subsoiling, of barley by 20% and of sugar by 4%. Mean yield of wheat was not further affected.


1980 ◽  
Vol 94 (3) ◽  
pp. 533-538 ◽  
Author(s):  
R. C. Sharma ◽  
J. S. Grewal ◽  
M. Singh

SummaryA long-term manurial experiment on potatoes was initiated in 1970 on the acidic brown hill soil of Simla to study the effects of fertilizers supplying per hectare: 44 kg P (P44); 44 kg P and 125 K (P44K125) and 88 kg P with 125 kg (P88K125) and of farmyard manure (FYM) supplying 44 kg P/ha applied annually and biennially. The potatoes gave large responses to all the manures. The annual or biennial effects of FYM measured in years of application were as great as that of P and K fertilizer in increasing tuber yield and K uptake by tubers but FYM increased P uptake more than fertilizers did. FYM applied each year gave largest uptake of P. P88 treatment was not better than P44 treatment. The residual effects of the manures on yield were measured in years when the treatments were not applied; the residual effects of FYM were higher than those of fertilizers. Mean residual effects of the treatments on P uptake were 46% and 51% of their annual or biennial effects respectively. About 90% of P added to the soil was not taken up by the crops and was present in the forms of aluminium-bound P, iron-bound P and calcium-bound P in this descending order. The residual effects of the treatments on K uptake were about 84% of their annual or biennial effects. About 60% of K applied to the soil was not taken up by the crops and most was present in exchangeable form. Annual applications of all the manures were better than their biennial applications indicating that residual effects built up from three applications over 6 years were too small to sustain yields.Soil analyses made 6 years after the start of the experiment showed that FYM was a better source of P than single superphosphate in increasing soil available P. FYM also increased soil exchangeable K more than the K fertilizer did. The highest increase in available P and K in soil was from annual applications of manures. Biennial applications of P as superphosphate or FYM resulted in P accumulating in the soil, while biennial K fertilizer dressings did not increase exchangeable K; however, biennial FYM did increase exchangeable K. Using P alone reduced soil available K. FYM increased pH, organic carbon and total N in soils while P and K fertilizer increased only the pH.


1983 ◽  
Vol 63 (2) ◽  
pp. 211-219 ◽  
Author(s):  
L. D. BAILEY

The objectives of the study were to determine the effect of soil and fertilizer potassium (K) on the yield and chemical composition of alfalfa (Medicago sativa L.), and whether fall harvesting (October) had detrimental effects on alfalfa grown under the relatively cool and short growing season of the Eastern Canadian Prairies. Vernal alfalfa was sown on five soils, two high and three low in amounts of exchangeable K. Three harvests were taken each year in June, July, and October at the full bud stage. The soils were rated on their potential potassium supplying power (PKSP). The effect of fertilizer K on increasing the availability of soil K and on the K and N composition of the forage were measured. The PKSP of the soils was not related to initial levels of exchangeable K. However, soils with low exchangeable K and low PKSP required an annual application of 200 kg K/ha to produce maximum yield. There was response to K fertilizer on only one of the soils with high exchangeable K, and then only to the first increment. At maximum yield on all soils, the K and N contents of the forage at full bud were greater than 2.0% and 3.0%, respectively. When the K content of the forage was less than 1%, severe winter injury occurred and yields decreased. With adequate K fertilizer fall harvesting had no detrimental effects on alfalfa production. Comparisons of the K and N contents of the forage indicates that increasing the concentration of K available to the crop may have a beneficial effect on N-fixation. Key words: Medicago sativa L. ’Vernal’, potential potassium supplying power, nitrogen fixation


1966 ◽  
Vol 46 (1) ◽  
pp. 23-28 ◽  
Author(s):  
D. K. Acquaye ◽  
A. J. MacLean

Ammonium applied alone or after addition of K depressed the uptake of K by oats grown in a sandy loam soil in the greenhouse. When NH4 was added first and K later at seeding, however, NH4 increased K-uptake.In the absence of K fertilizer, NH4 reduced the release of non-exchangeable K to the plants. When added prior to or at the same time as K at seeding, NH4 reduced K-fixation. This inhibitory effect of NH4 on fixation of added K was reflected in higher amounts of K in solution as shown by lower [Formula: see text] ratios. These results of chemical extraction of the soil indicated that the effects of NH4 on K-uptake by the oat crop arose from reactions in the soil.


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