1995-97 Tillage Study Summary and Yields

The experimental design is a randomized complete black (RCB) with four replications. Each crop block is 90 feet wide by 260 feet long. Each tillage treatment randomized within each crop block is 30 feet wide by 260 feet long.

The dates, varieties, herbicides used etc. are described within each of the yield discussions for the three crops.

The combined analysis of the yield results was performed using the M-stat program. Years were considered random events. As observed in Table 1 there was no significant effect of tillage or no tillage on wheat yields.

Table 1. 1995-1997 Combined Wheat Yields by Tillage Treatment Following Soybeans

Tillage Treatment            Yield (bu/ac at 13% moisture)
----------------------------------------------------------
1. No-till                              47 NS
2. No-till                              46 NS
3. Disk                                 47 NS
NS at .05 level of probability
CV = 5.22%

This section discusses only the corn yields for 1996 and 1997. The 1995 corn plot yields were confounded by herbicide drift. The only two tillage treatments that can be compared are (2) no-till corn following D/C soybeans and (3) chisel plow/disk of wheat residue. The other no-till treatment of red clover was only initiated in 1996 and has just one year of yield data.

The corn hybrids used in 1996 was Pioneer 3394 and in 1997 Pioneer 3335. Seeding rate is set at 27,000 kernels/acre. Kernel-gard seed treatment is used for potential soil insect problems. Pounce at the recommended rate is applied with the corn herbicides as a preventive measurement for black cutworm infestations. The planter used is a John Deere 7000 no-till planter. Yetter residue managers are used in front of the coulters for the two no-till plots and are not used for the reduced tillage treatment.

Stand counts are taken 4-6 weeks after planting. The 1996 stand counts for the two tillage treatments were 25,400 plants/acre for the reduced tillage treatment and 24,800 for the D/C soybean treatment. The stand counts in 1997 were 23,300 plants/acre for the reduced tillage treatment and 23,800 plants for the D/C soybean treatment.

Nitrogen as ammonium nitrate was applied at 160 lbs./acre in 1996 and at 200 lbs./acre in 1997. Weed control is obtained by a pre-emerge application of Bicep at 3.2 qts./acre and followed post-emergence for additional broadleaf control with an atrazine/Buctril tank mix. Harvest dates were Oct. 30, 1996 and Oct. 1 , 1997.

The double crop soybean no-till treatment is performed drilling a minimum of 300,000 soybean seed/acre. The soybeans are harvested in November. Double crop soybean yields averaged across the four replications made 7.5 bu/acre in 1996 and 17 bu/acre in 1997.

Table 2. 1996-1997 Combined Corn Yields by Tillage Treatment Following Wheat

Tillage Treatment             Yield (bu/ac at 15.5% moisture)
-------------------------------------------------------------
2. No-till-D/C Sb                        135 NS
3. Chisel plow/Disk                      137 NS
NS at .05 level of probability
CV = 7.06 %

As a result only bare wheat straw was the residue cover for this no-till treatment. The 1996 yields indicated a significant difference between the corn yields no-tilled into wheat residue (135 bu/acre) versus the no-tilled D/C Soybean treatment (156 bu/acre) and the Chisel plow/Disk treatment (160 bu/acre).

The addition of some type of a legume into the wheat residue seems to provide a rotational effect that that improves corn yields versus where no legume ie soybeans is used.

The soybean varieties used were Asgrow 3431 in 1995 and Maverick in 1997. Seeding rate is 200-225,000 seed/acre. The treatments are drilled in 8 inch drill spacings using a 10 foot Great Plains no-till drill. The planting date were June 20, 1995 and May 17, 1997

Weed control has been generally good. A post-emergence herbicide program is used. Harvest dates were October 17, 1995 and October 1, 1997.

The combined yield results for 1995 and 1997 as observed in Table 3. indicate no real yield differences as a result of tillage treatment.

Table 3. 1995 and 1997 Combined Soybean Yields by Tillage Treatment Following Corn

Tillage Treatment         Yield (bu/ac at 13.0% moisture)
---------------------------------------------------------
1. No-till                           42 NS
2. No-till                           42 NS
3. Chisel plow/Disk                  39 NS
NS at .05 level of probability
CV = 4.59 %

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