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1.
Abstract

Four liming and Mg materials were compared in a greenhouse experiment with soybeans for their ability to raise soil pH, supply Mg, and their effect on the availability of Mn, Cu, Fe, and Zn. Three materials were added at rates of 0, 1, and 2 times the lime requirement, calcitic lime, dolomitic lime, and Hydra‐Mag (an industrial by‐product containing 20% Mg). Sul‐Po‐Mag was the fourth material added as a plus Mg check at a rate based on an equivalent amount of Mg to that supplied by Hydra‐Mag. Plant growth, plant tissue element content and extractable soil elements were determined after growing the soybeans for 5 weeks. Plants in treatments where no lime/Mg materials were added were very small due possibly to Mg deficiency and Al toxicity. The 1 and 2 times rates of the materials gave about equal growth except that the high Sul‐Po‐Mag rate caused salt injury. Hydra‐Mag increased soil pH more than calcitic lime which increased soil pH more than dolomitic lime. Soil and plant Mg levels were increased more by Hydra‐Mag than dolomitic lime when applied at equivalent rates based on the lime requirement. Dolomitic lime gave very good plant growth indicating that it made adequate amounts of Mg available. Hydra‐Mag reduced plant and extractable soil Zn, Cu, and Fe but no more so than calcitic or dolomitic lime. Hydra‐Mag reduced plant Mn more than for the other limes.  相似文献   

2.
Abstract

Acid soil limitations to plant growth were assessed In 55 horizons of 14 major Appalachian hill land soils. Aluminum sensitive “Romano” and Al‐tolerant “Dade” snapbeans (Phaseolus vulgaris L.) were grown for 5 weeks in limed and unlimed treatments of the 55 horizons. Shoot and root growth was depressed >20% in unlimed relative to limed treatments in approximately 2/3 of the horizons. Dade snapbeans were generally more tolerant of the acid soil conditions and had higher Ca concentrations in the shoots than Romano snapbeans. However, the sensitive‐tolerant snapbean pair could not consistently be used to identify horizons with soil Al problems. Growth of both snapbeans was generally best in A horizons and worst in E horizons. The E horizons in this study were characterized by low Ca saturation (exchangeable Ca x 100/cation exchange capacity) and high Al saturation (exchangeable Al x 100/cation exchange capacity). Exchangeable Ca, soil Ca saturation and total soil solution Ca were positively correlated (p<0.01) with snapbean root and shoot growth. Soil Al saturation, total soil solution Al and soil solution Al reacting in 15 seconds with 8‐hydroxyquinoline were negatively correlated (p<0.01) with growth. The ratio of Ca/Al in soil solution was more closely related to snapbean growth than the soil solution concentration of any individual element. Soil and soil solution Mn were, in general, not significantly correlated with snapbean growth. Many of the horizons in this study had both Al toxicity and Ca deficiency problems and interaction between Ca and Al affected both snapbean growth and Ca uptake. These findings confirm the importance of considering Ca as well as Al when investigating Al phytotoxicity.  相似文献   

3.
In a ten‐year study of potassium (K) and lime application to a Kalmia sandy loam (fine‐loamy, siliceous, thermic Typic Hapludult), a soil high in nonexchangeable K, corn (Zea mays L.) and soybean [Glycine max (L.) Herr.] have not responded to applied K. The objectives of this study were to determine if a high K‐requiring crop such as tomato (Lycocersicon esculentum Mill. cv. Redpak) would respond to KCl fertilizer rate or lime type (dolomitic, calcitic, and mixed) and rate on such a soil. Potassium was applied at 0, 56, and 112 kg K/ha every year for ten years. Lime was applied at 0, 2, and 9 Mg/ha in calcitic, mixed, and dolomitic forms twice in ten years (1970 and 1973). In 1980, the tenth year of the study, tomato fruit was harvested by hand once‐over to simulate machine harvest and divided into four maturity groups by color. Soil pH was higher with dolomitic than calcitic lime. Soil K saturation was not influenced by lime rate or type. Fruit yield and leaf phosphorus (P), calcium (Ca), and magnesium (Mg) concentrations increased with increasing lime rates. Leaf K, manganese (Mn), iron (Fe), boron (B), copper (Cu), zinc (Zn), barium (Ba), strontium (Sr), and aluminum (Al) concentrations decreased with increasing lime rate. Leaf Mn, Ba, and Sr concentrations were lower with dolomitic than with calcitic lime. Lime type had no effect on tomato yield. Wide ranges in basic cation saturation ratios had little effect on yield. Soil K saturation and leaf K, Zn, and Ba concentrations increased with increasing K rate. Soil Ca and leaf Ca, Mg, and Al concentrations decreased with increasing K rate. Applied K had no effect on total yield but onceover marketable yield increased linearly with increasing K rate. Marketable yield increased 14% with an increase in K rate from 0 to 56 kg/ha. Thus, fruit maturity was apparently hastened by K fertilization.  相似文献   

4.
Abstract

Changes in surface reactivity produced by different types of liming in a Chilean Andisol were determined. Barros Aranas soil with 53% aluminum (Al) saturation and 4.8 pH was incubated with different amounts of calcitic and dolomitic lime. Each cmol of calcitic or dolomitic lime applied per kg of soil increased the pH with 0.13 and 0.16 units, respectively. Consequently, the decrease in Al saturation was higher with dolomitic than with calcitic liming material. The zero point of charge (ZPC) increased from 4.2 in unlimed soil to 4.6 and 4.8 in limed soil, while the point of zero salt effect (PZSE) decreased from 4.5 to 4.0 and 3.5 with calcitic and dolomitic lime, indicating an increase in negative charge. But, isoelectric point (IEP) values measured by electrophoretic migration suggested that the external charge only changed by treatment with calcitic liming materials. In both treatments, the acidity constant decreased, and consequently phosphorus (P) adsorption capacity also decreased.  相似文献   

5.
Abstract

The cost and difficulty of applying lime on hilly pastures or small forage fields makes it appropriate to devote attention to efficiency of lime utilization. This study evaluated effects of calcitic and dolomitic lime on yield and mineral composition of 11 forage species grown on soil with a low base status of 0.46 cmolc as Ca and 0.18 cmolc as Mg kg‐1. Both lime types increased dry matter production, but only Lolium multiflorum responded more positively to dolomitic lime. The low Mg level in the soil was not a major factor limiting yield. Increase in yield was mainly attributed to the increase in pH with the concurrent decrease in Al level and to an increased Ca availability to plants. The species ranked as follows according to the magnitude of yield increase due to calcitic liming: Trifolium fragiferum > Trifolium pratense > Vicia sativa > Vicia villosa > Trifolium repens > Lolium perenne > Lolium multiflorum > Festuca arundinaceae = Lolium (multiflorum x perenne x perenne) > Trifolium subterraneum > Dactylis glomerata. The most responsive, Trifolium fragiferum, did not grow without lime. The least responsive, Dactylis glomerata, showed a yield increase of 36%. A similar ranking was obtained when all species were evaluated for Al tolerance using a 48 hour root elongation bioassay. In both unlimed soil and soil limed with calcitic lime, Mg concentrations of all species were relatively low. Although they were generally not low enough to have an effect on yield, they barely met the Mg nutritional requirement of cattle. By adding dolomitic lime, Mg content increased in grasses an average of 3.7 fold and in legumes by 2.4 fold. Grasses were similar in Ca, Mg, and K concentrations within a soil treatment. Legumes showed a greater range with the two vetches having the lowest Ca and Mg concentrations and red clover the highest.  相似文献   

6.
Abstract

Since ryegrass (Lolium sp.) is a widely grown cool‐season forage grass, its magnesium concentration is of special interest to ruminant livestock producers. This study was conducted to investigate the effect of calcitic or dolomitic lime addition on dry matter yield and mineral composition of hybrid ryegrass, Lolium (multiflorum x perenne x perenne) grown in eight acidic soils. Each soil received two levels of calcitic or dolomitic lime, L(C1) and L(C2) or L(D1) and L(D2), which raised pH to approximately 5.3, and 6.0. Dry matter yield response was obtained only in soils having an initial % Al saturation ≥59, % Mg saturation ≤10 and % Ca saturation ≤21. Only in one soil, which had an initial exchangeable Mg level of 0.05 cmolc/kg of soil, was response to dolomitic lime higher than that obtained with calcitic lime. Magnesium concentration in dry matter was increased by both levels of dolomitic lime with the increase dependent on the rate used and on the initial level of exchangeable Mg. The average Mg concentration increased from 0.8 to 3.9 g/kg, from 1.6 to 3.6 g/kg, and from 2.6 to 3.9 g/kg, when ryegrass was grown in soils having low, medium, and high initial exchangeable Mg levels, respectively. Mg concentration in the ryegrass tended to be lower in the unlimed soils than when calcitic lime was used, 1.1 vs. 1.4 g/kg, when the soils had low to medium exchangeable Mg levels. The results suggest that if ryegrass is to be grown in acidic soils containing low to medium levels of exchangeable Mg, the use of dolomitic lime is desirable, even if no yield response to applied Mg is expected, to decrease the probability of the Mg deficiency disease, hypomagnesemia, in ruminant animals.  相似文献   

7.
Effect of integrated use of mycorrhiza, lime, inorganic fertilizers, and organic manures on microbial activities and yield performance of yam bean (Pachyrhizus erosus L.) was studied for two consecutive kharif (rainy) seasons during 2013–14 and 2014–15 in an acid Alfisol. The experiment was laid out with 16 treatments consisting of graded doses of soil test–based nitrogen, phosphors, and potassium (NPK); lime; mycorrhiza; organic sources, that is, farmyard manure (FYM), vermicompost, and green manure; secondary magnesium sulfate (MgSO4) and micronutrients zinc sulfate (ZnSO4 and borax). Significantly highest mean tuber yield (29.61 t ha?1) was recorded due to integrated application of lime + FYM + NPK + ZnSO4. Graded doses of NPK showed a mean yield response of 65%, 134%, and 191% due to addition of 50%, 100%, and 150% of NPK over control, respectively. Inoculation of vesicular–arbuscular mycorrhiza (VAM) combined with NPK and FYM recorded a mean tuber yield of 25.14 t ha?1. Highest mean dry matter (18.85%) was recorded due to application of 150% NPK, whereas highest starch content on fresh weight basis was recorded due to integrated use of lime + FYM + NPK + MgSO4 (11.11%). Application of 150% NPK has recorded highest dehydrogenase activity (2.018 µg TPF h?1 g?1) and fluorescein diacetate hydrolysis assay (2.012 µg g?1 h?1). Fungal inoculation of VAM in combination with lime + FYM + NPK recorded highest acid and alkaline phosphatase activities (82.20 and 67.02 µg PNP g?1 soil h?1, respectively). Soil biological activities and phosphatase activities had highly significant relationship with tuber yield and biochemical constituents of yam bean. The study emphasized the conjunctive use of soil test–based inorganic fertilizers, lime, and organic manures to enhance the enzymatic activities and to realize higher crop yields of yam bean in acid Alfisols.  相似文献   

8.
Abstract

High vater table sandy soils present special problems when establishing soil pH variables under field conditions. In order to examine the response of a coarse‐textured soil to lime and HC1 acid treatments, data are reported for soil pH and extractable Ca and Mg for a field experiment where Mn treatments on soybeans was the primary objective. Three treatments included HC1 acid, control, and lime. Acid (742 liters/ha 3N HC1) was added only at the beginning of the experiment but dolomitic lime treatments were added each year (2240, 2740, and 2900 kg/ha). The lime and acid were applied to the soil surface and incorporated to a depth of 10 to 13 cm. Soil samples were taken every 2 to 3 months at 3 depths (0 to 15, 15 to 30, and 30 to 45 cm) and analyzed for pH and extractable Ca and Mg. Acid treatment decreased the pH by 0.2 units below the untreated soil at the 0 to 30 cm depth and the effect lasted the entire 3 years of the study. Calcium values were lowered only slightly by the acid treatment. Lime additions caused steady increases in soil Ca. Magnesium values increased several months after each of the first and second lime applications. Lime raised the subsoil (30 to 45 cm) pH after 4 to 6 months. Seasonal variations in pH were very wide with the untreated soil pH varying from 6.1 to 6.8. The high pH level of 7.0 was not maintained for an entire season until the third year of the experiment. Soil pH as well as extractable Ca and Mg showed fluctuations that were the result of seasonal variations and soil moisture content at the time of sampling. Soil pH variables on a sandy soil should be established at least a year in advance of starting an experiment and must be closely monitored in order to maintain the desired pH levels.  相似文献   

9.
Imbalanced fertilizer use with intensive cropping has threatened the sustainability of agroecosystems, especially on acid soils. An understanding of the long-term effects of fertilizers and amendments on soil health is essential for sustaining high crop yields. The effects of application of fertilizers, and amendments for 46 years on soil properties and maize yield in an acid Alfisol were investigated in this study. Ten fertilizer treatments comprising different amounts of NPK fertilizers, farmyard manure (FYM) and lime, and one control, were replicated three times in a randomized block design. At 0–15 cm soil depth, bulk density was least (1.20 t/m3), porosity (49.8%) and water holding capacity (61.7%) were greatest in 100% NPK + FYM, corresponding to the largest organic carbon content (13.93 g/kg). Microbial biomass C and dehydrogenase activity in 100% NPK + FYM were 42% and 13.7% greater than 100% NPK, respectively. Available nutrients were significantly more with 100% NPK + FYM and 100% NPK + lime than control and other fertilizer treatments. At 15–30 cm depth, the effect of various treatments was comparable to the surface layer. Grain yield declined by 55% and 53% in 100% NPK(-S) and 100% NP, respectively, compared with 100% NPK, whereas 100% N as urea alone eventually led to crop failure. Soil porosity recorded the greatest positive correlation (r = .933**), whereas bulk density recorded a negative significant correlation (r = −.942**) with grain yield. The results suggest that integrated use of FYM/lime with chemical fertilizers is a sustainable practice in terms of crop yield and soil health, whereas continuous application of urea alone is detrimental to the soil health.  相似文献   

10.
Abstract

Soil applications of boron (B) generally had little effect on yield of carrots (Daucus carota L.) and beets (Beta vulgaris L.) in a field study. However, in a greenhouse study B significantly increased the yield of carrots. Boron deficiency impaired the quality of both crops. Boron deficient beets had brown tops and roots were rough, scaby, and off colour. There was a depression on the sides of most of the beet roots and cut sections of affected roots were darker and necrotic compared to bright purplish red roots grown with sufficient B. In carrots, B deficiency resulted in yellow tops and the roots were both rough and small with a distinct white core in the middle. Leaf tissue B concentrations of 32–40 μg/g in beets and 22–28 μg/g in carrots were related to B deficiency. Tissue B levels as high as 121 μg/g in beets and 149 μg/g in carrots were not associated with any B toxicity. Applications of B had no effect on tissue Ca and Mg concentration in the two crops.  相似文献   

11.
A field experiment was conducted for five kharif seasons (2006–2011) in an Alfisol to study the effect of integrated use of lime, mycorrhiza, and inorganic and organics on soil fertility, yield, and proximate composition of sweet potato. Application of graded doses of nitrogen, phosphorus, and potassium (NPK) significantly increased the mean tuber yield of sweet potato by 44, 106, and 130 percent over control. Green manuring along with ½ NPK showed greater yield response over that of ½ NPK. The greatest mean tuber yield was recorded due to integrated application of lime, farmyard manure (FYM), NPK, and MgSO4 (13.69 t ha?1) over the other treatments. Inoculation of mycorrhiza combined with lime, FYM, and NPK showed a significant yield response of 10 percent over FYM + NPK. Conjunctive use of lime, inorganics, and organics not only produces sustainable crop yields but also improve soil fertility, nutrient-use efficiency, and apparent nutrient recovery in comparison to NPK and organic manures.  相似文献   

12.
The aim of this experiment was to study the lime and gypsum reapplied on surface and their impacts on maize crop under the sole and intercropped systems. The experiment is being developed in a dystrophic Oxisol, since 2011, and arranged in a randomized blocks design, in split-split plots, with four replications. As treatments in the plots, the maize was installed in two cropping systems: sole and intercropped with Urochloa. For the subplots, we used four doses of lime (0, 2000, 4000, and 6000 kg ha?1) and four doses of gypsum (0, 1500, 3000, and 4500 kg ha?1) distributed at random in the sub-subplots. The combination of intermediate doses of lime and gypsum resulted in higher foliar Ca content. The grain yield increased with the combination of lime and gypsum. The maize when cultivated in intercropped system is more productive, with a point of maximum for dolomitic lime of 3031 kg ha?1.  相似文献   

13.
An experiment comprising seven treatments was conducted to study the effect of boron and lime integrated with organic manures and nitrogen, phosphorus, and potassium (NPK) fertilizers on garden pea productivity. Seed yield along with growth parameters were significantly influenced by combined use of farmyard manure and NPK fertilizers either alone or in combination with boron and lime. Treatment combination of 20 t farmyard manure / ha + 100% NPK + borax (T4) resulted in 37% increase in seed yield over recommended practice of 20 t farmyard manure / ha + 100% NPK (T3). In addition, recommended practice supplemented with granubor (T5) and lime (T6) also significantly surpassed T3 with respective increase of 14 and 10% in seed yield. Similarly, maximum nutrient was observed in T4. Hence, application of boron along with farmyard manure and NPK fertilizers could be the best option to maximize pea productivity in acidic soils under humid subtemperate climate.  相似文献   

14.
Crop response to fertilization and liming was investigated in field and pot trials on sandy loam Dystric Albeluvisols (pH 4.2–4.3). Treatments in the field trial were: 1, no fertilizer; 2, PK; 3, NK; 4, NP; 5, NPK; 6, lime; 7, lime+PK; 8, lime+NK; 9, lime+NP; 10, lime+NPK. In the pot trial, they were: 1, no fertilizer; 2, N; 3, P; 4, K; 5, NP; 6, NK; 7, PK; and 8, NPK applied to unlimed and limed soils. All treatments were in four replicates. Crops sensitive to soil acidity (winter wheat, fodder beet, spring barley and clover-timothy ley) and the less acid-sensitive winter rye, potatoes, oats and lupins and oats mixture were sown in the field trial. In the pot trial, the acid-sensitive spring barley and red clover, and the less acid-sensitive oats and lupin-oats served as the test crops. Combined application of fertilizers (NPK) increased yields of crops sensitive to soil acidity in plots receiving lime by 23%, and those of crops less sensitive to soil acidity by 18% in comparison to crops grown on unlimed soils. The results of pot experiments corroborated the field results. When N was applied alone, crop yields were always higher than those recorded for P or K treatments on both the unlimed and limed treatments. N application proved to be a prerequisite for high crop yields in the soils investigated. Thus, the efficiency of P and K fertilizers increased in the order NK<NP<NPK, with the effects being accentuated more in the limed than in the unlimed treatments. The results demonstrated the importance of multi-nutrient (NPK) fertilization in combination with liming for enhancement of high crop productivity in the unlimed soil investigated. N applied alone in combination with liming produced relatively good yields; hence, where resources are limited for the purchase of P and K fertilizers, applying N and lime can be a viable option in the short term.  相似文献   

15.
长期施肥及石灰后效对不同生育期玉米根际钾素的影响   总被引：2，自引：0，他引：2  
依托祁阳红壤旱地定位施肥试验(始于1990年),选取施氮磷(NP)、氮磷+石灰(NPCa)、氮磷钾(NPK)、氮磷钾+石灰(NPKCa)、氮磷钾配施秸秆(NPKS)、氮磷钾配施秸秆+石灰(NPKSCa)6个处理,采集玉米不同生育期根际与非根际土壤,测定其钾、钙、镁、铝含量和p H。结果表明:与NP处理相比,施钾处理(NPK和NPKS)根际和非根际土壤速效钾含量显著提高。NP、NPK和NPKS处理根际速效钾在拔节期和灌浆期均处于亏缺状态,亏缺率分别平均为18.2%、34.2%和26.4%。与对应不施石灰处理相比,NPKCa和NPKSCa处理根际土壤速效钾含量在苗期分别降低46.0 mg kg~(-1)和26.5 mg kg~(-1),非根际分别降低68.5 mg kg~(-1)和56.0 mg kg~(-1);从拔节期至收获期,根际速效钾含量平均升高25.2 mg kg~(-1)和33.7 mg kg~(-1),非根际略微降低。NPCa、NPKCa和NPKSCa处理根际土壤速效钾盈亏率与不施石灰相比,整个生育期分别平均提高8.6%、33.2%和19.3%。根际和非根际土壤速效钾含量与相对应缓效钾含量、钾饱和度、K+/(Ca2++Mg2+)和K+/Al3+呈极显著正相关关系。缓效钾和钾饱和度相对变化率(交换性钙镁相对变化率)与速效钾相对变化率呈极显著正(负)相关关系。长期施氮磷钾肥基础上施石灰(NPKCa和NPKSCa)4年以后,根际土壤速效钾、缓效钾含量及钾饱和度均提高(苗期除外),根际土壤交换性钙镁含量提高幅度低于非根际,最终缓解根际土壤钾素的亏缺。  相似文献   

16.
Abstract

Root crops constitute an important part in the diet of millions of people throughout the Tropics. These crops are produced by subsistence farmers in poor soils where acidity is the most common problem and liming materials, such as limestone, are scarce and expensive. Few experimental data are available on the fertility requirements and liming response of tanier (Xanthosoma sagittifolium). This study was conducted to determine the effect on yield of limestone application. Rates of 0, 1, 2, 3, and 4 t/ha of calcitic and dolomitic limestome, respectively, were applied in an Ultisol. Tanier shows tolerance to soil acidity with yields 58% a of maximum with 64% aluminum (Al) saturation. The limestone additions of 4 t/ha resulted in a pH of 4.38 and 4.68 with calcitic and dolomitic limestone, respectively, which produced the highest yield.  相似文献   

17.
In acid soils, when no-tillage farmers intend to apply lime, the question arises as to whether it should be incorporated into the soil or whether it can be left on the soil surface. In this study, two types of limestone, calcitic (Lcal) and dolomitic (Lmag), were tested in two olive groves of cv. Cobrançosa, with an initial pH of 4.9 (S. Pedro) and 5.5 (Raparigas). In S. Pedro, limestone was incorporated into the soil (Lburied) and in Raparigas, it was left on the floor (Lfloor). The use of limestone significantly increased soil pH in the 0–0.10 m layer in both experiments. In the 0.10–0.20 m soil layer, only Lmag increased significantly the soil pH in comparison with the control. Lmag was more effective than Lcal in increasing cation exchange capacity (CEC) and reducing exchangeable acidity (EA) and aluminium (Al3+) in the Lfloor experiment. Both limes increased leaf calcium (Ca) concentration, and Lmag increased the leaf levels of magnesium (Mg). In Lfloor experiment (higher soil pH), soil microbial carbon (C) decreased, and microbial nitrogen (N) increased with liming, which may indicate an increase in bacteria in the soil and a decrease in fungi. In Lburied experiment (initial pH of 4.9), liming significantly increased accumulated (2018–2021) olive yield (56 and more than 67 kg tree−1, respectively, in the control and liming treatments). In Lfloor experiment (initial pH of 5.5), the accumulated olive yields did not differ significantly between treatments (average values between 105 and 115 kg tree−1). The results of this study provide evidence that liming may increase olive yield in very acid soils and that dolomitic limestone should preferably be used by no-tillage farmers, due its higher solubility and faster effect on soil and trees.  相似文献   

18.
The inoculation of red beets with the nitrogen-fixing bacteria Pseudomonas putida 23 increased the activity of the nitrogen fixation in the rhizosphere of the plants grown on meadow soil in the central part of the Oka River floodplain. The yield of the red beets and the uptake by plants of nitrogen from the soil and from the 15N-labeled nitrogen fertilizer applied on the trial microplot increased significantly. A statistically significant additional fixation of nitrogen from the atmosphere and a positive balance of nitrogen in the soil-plant system without significant changes in the bulk content of the soil nitrogen after the plant growing were found in a greenhouse experiment with the application of P. putida. It can be supposed that the excessive nitrogen determined in this system is related to the incorporation into plants of atmospheric nitrogen fixed in the rhizosphere of the inoculated plants. The application of P. putida 23 makes it possible to decrease the rates of NPK fertilizer by two times without losses in the yield of red beets.  相似文献   

19.
Abstract

A long‐term double cropping wheat (Triticum aestivum L.) and corn (Zea mays L.) experiment was conducted at Qiyang, Hunan, China, to study the effects of inorganic fertilizers on grain yields and soil properties and to identify the possible causes of yield trends. Six treatments of unfertilized control, N, NP, NK, PK, and NPK were included. The treatments (N, NP, NK, and NPK) where inorganic nitrogen (N) was added showed significant (P<0.05) yield declines of 76 to 114 kg ha?1 yr?1 for wheat and 94 to 260 kg ha?1 yr?1 for corn, respectively, except for corn yield in the NPK treatment in which the decline was not significant during a 15‐yr (1990–2005) period. Comparatively, the decline amounts in corn were much higher than in wheat. The yields of wheat and corn remained unchanged in the PK treatment. The total organic carbon (C), total N, phosphorus (P), and available P, potassium (K), copper (Cu), and zinc (Zn) contents of soil were either increased or decreased during the study period. Both the decreases of exchangeable calcium (Ca2+) and magnesium (Mg2+) and increases of exchangeable hydrogen (H+) and Al3+ contents of soil in the treatments where inorganic N was applied were significant (P<0.05). The same four treatments showed significant pH declines ranging from 0.07 to 0.12 yr?1. Several lines of evidence point to decline of soil pH due to inorganic N fertilizer added as leading to the overall yield decline of wheat and corn. However, the yields of both crops increased significantly after lime application. In the long term, the farmers should be encouraged to use adequate lime based on a balanced approach to ensure sustainable productivity.  相似文献   

20.
Abstract

Maximum yields of red clover, alfalfa, and birdsfoot trefoil were obtained when 0.25 to 1.0 ppm B was added to the soil. An application of lime to raise the soil pH to 5.8–6.3 improved yields, while at pH 6.8 a decline in yield in the first and second cuts of birdsfoot trefoil was noted. There was a marked B x lime interaction on the yield of all cuts of birdsfoot trefoil and first cut of red clover, with much higher yields with high rates of lime at high rates of added B.

Levels of 4 to 9 ppm B in the leaf tissue of the three crops were in the deficiency range. Boron concentrations of 21 to 45, 39 to 52, and 30 to 45 ppm in the first cuts of red clover, alfalfa, and birdsfoot trefoil were indicative of sufficiency and were associated with maximum yields, while levels of >59, >99, and >68 ppm, respectively, in the three crops were in the toxicity range. Sufficiency levels of soil B for legumes appeared to be related to pH since B deficiency was more severe at higher pH than at lower pH. Liming of soil from pH 5.3 to 6.8 resulted in decreased concentration of B in all the three crops with the smallest decreases in alfalfa. There was a marked B x lime interaction on the B concentrations of the three crops, with much higher B concentrations in high B treatments at low soil pH than at high pH values.  相似文献   

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