Foliar Potassium Fertilizer Additives Affect Soybean Response and Weed Control with Glyphosate

Table 3

The effect of fertilizer additive on soybean injury 3 d after treatment (DAT) in the presence and absence (weed-free) of glyphosate, and total weed dry weight reduction of fertilizer additives tank-mixed with glyphosate at Novelty 28 DAT in 2004 and 2005. Data were combined over years^a.

Fertilizer additive^c	Rate	Injury 3 DAT		Total weed^b dry weight reduction
	(Kg K ha^−1)	Weed-free	Glyphosate tank mixture	Glyphosate tank mixture
		(%)		(%)
Non-treated		0		0
Weed-free		0	—^d	100
NIS		—	1	93
NIS + DAS		—	1	93
	2.2	0	1	88
0-0-62-0	8.8	2	3	91
	17.6	6	6	90
	2.2	0	0	96
3-18-18-0	8.8	1	3	96
	17.6	4	3	88
	2.2	1	1	88
0-0-25-17	8.8	3	5	86
	17.6	5	6	84
	2.2	0	1	96
5-0-20-13	8.8	4	6	87
	17.6	6	6	85
LSD (𝑃=0.01)		2		11

^aAbbreviations: DAS: diammonium sulfate; NIS: non-ionic surfactant.
^bWeed species included common lambsquarters in 2004, common ragweed in 2005, common waterhemp in 2004 and 2005, and giant foxtail in 2004 and 2005.
Total dry weight reduction was calculated as 100(1−(totalweeddryweight/untreatedweeddryweight)).
^cFertilizer additives included 3-18-18-0 as %N-%P₂O₅-%K₂O-%S, K phosphate + urea (NA-CHURS/ALPINE); 0-0-25-17, K thiosulfate; 5-0-20-13, K thiosulfate + urea-triazone (Trisert-K+, Tessenderlo Kerley); and 0-0-62-0, potassium chloride. All fertilizer additives with glyphosate included non-ionic surfactant.
^dTreatment was not included.