Abstract
Abstract Arrowleaf clover ( Trifolium vesiculosum Savi ‘Yuchi’) is a winter annual legume that can be used to extend the grazing of warm‐season perennial grasses in forage production systems. Stand establishment from overseeding often fails because of unfavorable climatic conditions and nutrient deficiencies in soils. The objectives of this research were to determine the effects of P and K fertilization on yield and nutrient uptake of arrowleaf clover and accumulation of soil P and K. Arrowleaf clover was seeded in field plots in the fall of 1978. Fertilizer treatments consisted of an incomplete factorial arrangement of multiple rates of P, K, and P plus K. Rates of P and K included a control that did not receive fertilizer; 20, 40, and 80 kg P ha −1 ; 37, 74, and 148 kg K ha −1 ; and P‐K combinations of 20:37, 40:74, and 80:148 kg ha −1 . The soil type was a Taloka silt loam (Mollic Albaqualfs). Yield and N, P, and K uptake in forage were determined in four consecutive years starting in 1979. Soil test indices were measured prior to seeding in 1977, in the fall of 1978, and after four annual fertilizations in 1982. Regression equations with linear, quadratic, and interaction terms were calculated to describe dependent variable response surfaces for each year and the average over years. Phosphorus fertilization increased yield each year. Yield was not increased with K fertilization alone, but there was a positive P × K interaction in the 1982 season indicating soil K levels were decreasing. Predicted maximum yields were 6561, 6490, 6516, and 6860 kg ha −1 due to applications of 50.8, 52.4, 54.0 and 57.2 kg P ha −1 , respectively, at fixed rates of 0, 37, 74, and 148 kg K ha −1 . Phosphorus increased N, P, and K uptake and when applied in combinations with K, some interactions occurred. The soil test index for P increased slowly (0.5 kg ha −1 yr −1 ) with P rates of 20 kg ha −1 annually; however, a rapid accumulation of soil P occurred with four annual applications of 80 kg P ha −1 (16.5 kg ha −1 yr −1 ). Approximately 107, 16, 6, and 3 annual applications of 20, 40, 60, and 80 kg P ha −1 , respectively, would be required to increase soil test values for P to a sufficient level. Soil test values for K were increased from 133 to 308 kg ha −1 with four annual applications of 148 kg K ha −1 . However, after four annual applications of 80 kg P ha −1 in combination with 148 kg K ha −1 , the soil test value for K was only increased to 192 kg ha −1 due to the marked response from P fertilization and subsequent increase of K removal in forage.
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Claims 17
Claim · model-written summary
Phosphorus fertilization increased clover yield each year.
Not reportedComparator
Verbatim
e0“Phosphorus fertilization increased yield each year”
t0“Arrowleaf Clover”
Claim · model-written summary
Potassium fertilizer alone did not increase clover yield.
Not reportedComparator
Verbatim
e0“Yield was not increased with K fertilization alone”
t0“Arrowleaf Clover”
Claim · model-written summary
P and K interacted positively for yield in 1982.
Verbatim
e0“there was a positive P × K interaction in the 1982 season”
t0“Arrowleaf Clover”
e1“Yield was not increased with K fertilization alone”
Claim · model-written summary
At zero K, predicted maximum yield was 6561 kg ha−1 with 50.8 kg P ha−1.
Verbatim
e0“Predicted maximum yields were 6561, 6490, 6516, and 6860 kg ha −1 due to applications of 50.8, 52.4, 54.0 and 57.2 kg P ha −1 , respectively, at fixed rates of 0, 37, 74, and 148 kg K ha −1”
t0“Arrowleaf Clover”
Claim · model-written summary
At 37 kg K, predicted maximum yield was 6490 kg ha−1 with 52.4 kg P ha−1.
Verbatim
e0“Predicted maximum yields were 6561, 6490, 6516, and 6860 kg ha −1 due to applications of 50.8, 52.4, 54.0 and 57.2 kg P ha −1 , respectively, at fixed rates of 0, 37, 74, and 148 kg K ha −1”
t0“Arrowleaf Clover”
Claim · model-written summary
At 74 kg K, predicted maximum yield was 6516 kg ha−1 with 54.0 kg P ha−1.
Verbatim
e0“Predicted maximum yields were 6561, 6490, 6516, and 6860 kg ha −1 due to applications of 50.8, 52.4, 54.0 and 57.2 kg P ha −1 , respectively, at fixed rates of 0, 37, 74, and 148 kg K ha −1”
t0“Arrowleaf Clover”
Claim · model-written summary
At 148 kg K, predicted maximum yield was 6860 kg ha−1 with 57.2 kg P ha−1.
Verbatim
e0“Predicted maximum yields were 6561, 6490, 6516, and 6860 kg ha −1 due to applications of 50.8, 52.4, 54.0 and 57.2 kg P ha −1 , respectively, at fixed rates of 0, 37, 74, and 148 kg K ha −1”
t0“Arrowleaf Clover”
Claim · model-written summary
Phosphorus increased forage N, P and K uptake.
Not reportedComparator
Verbatim
e0“Phosphorus increased N, P, and K uptake”
t0“Arrowleaf Clover”
Claim · model-written summary
Combining phosphorus and potassium produced some uptake interactions.
Verbatim
e0“when applied in combinations with K, some interactions occurred”
e1“Phosphorus increased N, P, and K uptake”
t0“Arrowleaf Clover”
Claim · model-written summary
Annual P at 20 kg ha−1 slowly increased the soil P index by 0.5 kg ha−1 yr−1.
- Treatment
- P rates of 20 kg ha −1 annuallye0
- Outcome
- soil test index for Pe0
- Direction
- increasede0
- Value
- 0.5 kg ha −1 yr −1e0
Not reportedTaxonComparator
Verbatim
e0“The soil test index for P increased slowly (0.5 kg ha −1 yr −1 ) with P rates of 20 kg ha −1 annually”
t0“Arrowleaf Clover”
Claim · model-written summary
Four annual P applications at 80 kg ha−1 rapidly accumulated soil P at 16.5 kg ha−1 yr−1.
- Treatment
- four annual applications of 80 kg P ha −1e0
- Outcome
- soil Pe0
- Direction
- accumulatione0
- Value
- 16.5 kg ha −1 yr −1e0
Not reportedTaxonComparator
Verbatim
e0“a rapid accumulation of soil P occurred with four annual applications of 80 kg P ha −1 (16.5 kg ha −1 yr −1 )”
t0“Arrowleaf Clover”
Claim · model-written summary
Approximately 107 annual applications of 20 kg P ha−1 were predicted to reach sufficient soil P.
Not reportedTaxon
Verbatim
e0“Approximately 107, 16, 6, and 3 annual applications of 20, 40, 60, and 80 kg P ha −1 , respectively, would be required to increase soil test values for P to a sufficient level”
t0“Arrowleaf Clover”
Claim · model-written summary
Approximately 16 annual applications of 40 kg P ha−1 were predicted to reach sufficient soil P.
Not reportedTaxon
Verbatim
e0“Approximately 107, 16, 6, and 3 annual applications of 20, 40, 60, and 80 kg P ha −1 , respectively, would be required to increase soil test values for P to a sufficient level”
t0“Arrowleaf Clover”
Claim · model-written summary
Approximately six annual applications of 60 kg P ha−1 were predicted to reach sufficient soil P.
Not reportedTaxon
Verbatim
e0“Approximately 107, 16, 6, and 3 annual applications of 20, 40, 60, and 80 kg P ha −1 , respectively, would be required to increase soil test values for P to a sufficient level”
t0“Arrowleaf Clover”
Claim · model-written summary
Approximately three annual applications of 80 kg P ha−1 were predicted to reach sufficient soil P.
Not reportedTaxon
Verbatim
e0“Approximately 107, 16, 6, and 3 annual applications of 20, 40, 60, and 80 kg P ha −1 , respectively, would be required to increase soil test values for P to a sufficient level”
t0“Arrowleaf Clover”
Claim · model-written summary
Four annual 148 kg K ha−1 applications raised soil K from 133 to 308 kg ha−1.
- Treatment
- four annual applications of 148 kg K ha −1e0
- Outcome
- Soil test values for Ke0
- Direction
- increasede0
- Value
- 133 to 308 kg ha −1e0
Not reportedTaxonComparator
Verbatim
e0“Soil test values for K were increased from 133 to 308 kg ha −1 with four annual applications of 148 kg K ha −1”
t0“Arrowleaf Clover”
Claim · model-written summary
Combining four annual 80 kg P and 148 kg K applications raised soil K to only 192 kg ha−1.
- Treatment
- 80 kg P ha −1 in combination with 148 kg K ha −1e0
- Outcome
- soil test value for Ke0
- Direction
- increasede0
- Value
- 192 kg ha −1e0
Not reportedTaxonComparator
Verbatim
e0“after four annual applications of 80 kg P ha −1 in combination with 148 kg K ha −1 , the soil test value for K was only increased to 192 kg ha −1”
t0“Arrowleaf Clover”