ISSN:
1573-0867
Keywords:
China
;
Guangdong Province
;
subtropical
;
ultisols
;
magnesium deficiency
;
subterranean clover
;
lime
;
boron
;
Mg/K ratio
Source:
Springer Online Journal Archives 1860-2000
Topics:
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Abstract Severe symptoms observed in clover pastures sown in north Guangdong Province, China, warranted study of the response to Mg fertilizer, and possible interactions with lime and B fertilizer. Subterranean clover (Trifolium subterraneum) was sown in a 2 × 2 × 2 factorial pot experiment with Mg, lime, and B treatments and four replications. The highly acid soil collected from Lechang Model Cattle Farm was low in exchangeable Mg (0.06 meq 100 g−1). Mg fertilizer doubled exchangeable Mg, increased Mg saturation to 〉 3% and raised the Mg/K ratio to 〉 1.0, but A1 saturation remained above 75%. Lime application doubled exchangeable Ca and reduced A1 saturation to 〈 1%, but did not affect exchangeable Mg or K levels. Clover yield increased (P 〈 0.01) with Mg application at 100 kg Mg ha−1, but was not affected by lime or B fertilizer. Regression analyses showed that exchangeable Mg, soil Mg/K ratio, and Mg concentration in tops each accounted for 〉 70% of yield variation. Yield decreased markedly when exchangeable Mg was 〈 0.22 meq, soil Mg/K ratio was 〈 1.0, and when Mg in top growth fell below 0.15%. Symptom scores for Mg deficiency (including reddening and necrosis on older leaves) were correlated with yield (R2 = 0.88) and tissue Mg (R2 = 0.92). Plants without symptoms were present only where tissue Mg was 〉 0.26%. Liming to amend soil acidity did not increase tissue Mg or correct deficiency symptoms in clover plants without added Mg, but did reduce P and B to below critical levels. B deficiency did not limit pasture growth and application of 4 kg B ha−1 was sufficient to raise B level in clover tops to 〉 25 mg kg−1 on lime amended soil. The implications of correction of this acute Mg deficiency in relation to future fertilizer programs (especially K fertilizer) for crops and pastures grown on China's weathered red soils is discussed, as are the problems associated with grazing livestock on Mg deficient pastures.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01048787
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