Trial location: San Agustín, Cruz Alta (Tucumán)
Monte Redondo Experimental Substation. EEA Obispo Colombres
Trial carried out within the INTA-BIAGRO Technological Agreement

Professionals in charge: Ing. A. Stegmayer, Ing. J. Amigo, Ing. J. Cajal, C. Funes (UN Tucumán). Ing. M. Devani, J. Lenis, (EEAOC) Ing. Alejandro Perticari, Ing. Juan C. Pacheco Basurco. (IMYZA-INTA-Castelar). Ing. Roberto Echegaray (Laboratorios Biagro S.A.). Special collaboration in the studies related to the occupation of strains introduced in nodules: Dr. María Florencia Del Papa, Dr. Antonio Lagares. (IBBM UNLP).

History and characteristics of the plot: Previous crops: For 20 years in a row there has been a rotation of soybean with corn (4 years soybean and 1 year corn), without fertilisations. The immediately previous agricultural cycle was corn. Population of specific bacteria soybean nodulation: > 100,000 bac/g. of soil (NMP). Soil characterisation: Compound samples were taken and sent to the Soil Institute of the INTA Castelar. Results: OM = 2.89%. CO = 1.68%. NO = 0.17%. C/N = 9.9 Passim = 34.1 ppm. CE = 0.66 mS/cm pH = 6.6 The soil is a typical argiustol with well drained phase, A class without limitations in topography, soil and drainage.

Sowing method: Conventional tillage. (Note: the last 6 year of the rotation there was direct drilling. For this specific trial, the land was ploughed with disks and successively with spike-tooth harrow to leave it ready for planting) Seed: GM 8. VC A-8000 RR. Planting date: January 4th, 2001. Inoculating method: INTA-BIAGRO preinoculation (Nodulest 10 inoculant + Biagro S1 adhesive + Biagro S2 additive). Weed and plague control: In land left fallow 2-4 D, 0.5 l/ha + Roundup 3 l/ha. In postemergency 2.7 l/ha of Roundup. Plagues: first application, pyretrine 100 cm3/ha and second application pyretrine 50 cm3/ha + thiodam 0.5 l/ha.

Experimental design:

Randomised blocks. Five (5) repetitions in plots 5.5 yards long and 4 rows with 20 inches of row spacing. Plots and blocks separated by less than 40 inches.

Nodule observation: 8 plants R5 were taken from each plot (See comments). For the analysis of the percentage of occupation in the nodules of the strains introduced by the inoculant, samples of 8 nodules of the main root per plant were taken (about 64 nodules per plot). Around 300-400 nodules were processed for treatment and sent to the IBBM-UNLP.

Strains used: The strains used for the trial from the collection of the IMYZA-INTA-Castelar were specially prepared by Laboratorios Biagro S.A. and formulated following the protocol for Nodulest 10 inoculant to be used with the INTA-BIAGRO preinoculation technology.

Strains: E109, S5079, S5080, Tucumán 1, Salta 1. Note: as requested by Ing. A. Stegmayer, one strain belonging to the regional isolation called FAZ2 was incorporated. The inoculant prepared by Ing. A. Stegmayer was a sterile peat-based one and the inoculating procedure was the same as the one for the other preinoculated treatments.

Treatments:
1- Uninoculated
2- Uninoculated and fertilised with 400 N units (divided in 5 applications of 80 UN: planting, V2, V4, R1, R3)
3- E109 double dose.
4- Tucumán 1 double dose.
5- Salta 1 double dose.
6- S5079 double dose.
7- S5080 double dose.
8- FAZ2 double dose. Rainfalls: January, 2001: 268mm. February, 2001: 106mm. March, 2001: 211mm. April, 2001: 96mm. May, 2001: 0mm. until harvest.

Harvest date: May 8th, 2001.

Harvest: 26 linear feet of row in each plot. Cultivable area = 13.5 ft2. Density = 6 plants/linear feet.

Comments: There are two additional treatments that will not be considered this time because they are two liquid commercial products used in the region for which no identification of the strains used has been made. The aim of this trial is to evaluate the performance of the isolated strains and identify them in order to use them in the region with the INTA-BIAGRO preinoculation technology for a validation of previous trials.

Summary chart with up-to-date analysed data (the data is expressed as an average for each strain):

The bar chart describes the level of response for the preinoculated treatments against uninoculated ones in a soil with a naturalised population of specific soybean-nodulating bacteria that will be identified and characterised at the IBBM.   Tucumán 2000/2001: Nodulest 10 INTA-BIAGRO Preinoculation Strains