Anderson, D.W.

Wilkinson, D.B.

English

eCommons@USASK

Productivity studies in the Weyburn map area

University of Saskatchewan Research Archive

- 66 -Productivity Studies in the Weyburn Map Area D.W. Anderson and D.B. Wilkinson Saskatchewan Institute of Pedology University of Saskatchewan Saskatoon, Saskatchewan INTRODUCTION The Saskatchewan Institute of Pedology is currently revising the soil survey of that portion of Saskatchewan covered by Report Number 12, producing maps of larger scale, increased detail and with more precise separations of the soils into associations and m~p units. To assess the significance of the more precise classifi-cation a study of the comparative agricultural productivity of the different soil series or profiles was initiated in the Weyburn Map Area. Because of the importance of Solonetzic soils in this ~rea the study concentrated on comparing the productivity of the differ~nt types of Solonetzic soils, weakly developed Solonetzic or SolonetzAc-Chernozemic intergrade types and normal Chernozemic soils. Additi~nal objectives of the study were to obtain basic data relating yield tq soil and other environmental properties to serve as inputs for a ' predictive model for crop production, and to assess the practicabi]ity f of lengthening crop rotations on Dark Brown Chernozemic soils. ' METHODS Five sites approximately 20-25 ha in area were selected (Tabl~ 1). At each site two representative transects were chosen and profiles typical of different soil series were selected at random. There were 15 profiles or plots at each site, generally five replicates of th~ three most commonly occurring series (Figure 1). At each plot soils were sampled to 60 em depth at seeding and available plant nutrien~s, salinity levels and pH were measured. Access tubes were installedf for monitoring soil moisture with the neutron moisture meter at 18~day intervals through the growing season. Crop condition was observed) at similar intervals. Precipitation was measured and recorded by dhe cooperating farmers. Estimates of total and grain yields were obtJined by sampling duplicate square meter areas. After harvest soil pits( were dug, soil profiles described and the Band C horizons sampled: to 1.2 m depth. Wheat on summerfallow was grown at all sites with the normal management practised by the farmer cooperators. The soil profiles or series studied were: AMA - Orthic Dark Brown, Amulet Association BKW - Solonetzic Dark Brown, Brooking Association BKY - Solodic Dark Brown, Brooking Association TCS - Dark Brown Solonetz, Trossachs Association TCT - Dark Brown Solodized-Solonetz, Trossachs Association TCU - Dark Brown Solod, Trossachs Association - 67 -Table 1. S.E. Productivity Study - 1975. Growing Cooperator Location Season Series II of kg/ha Prec. (rnrn) Replicates Yield H. Schnell 1 & 12-1-12-2 278 AMA 4 2650 BKY 4 2312 BKW 6 2171 TCU 1 2162 *H. Halverson s~-36-1-12-2 175 BKW 1 2606 TCU 5 2343 TCS 5 2278 TCT 4 1893 H. Lievaart NW-6-2-10-2 180 BKY 1 2401 BKW 3 2115 TCU 4 2084 AMA 3 2002 TCS 4 1602 *K. Memory NW31-l-10-2 176 BKW 1 3017 BKY 1 2253 TCU 4 2100 TCS 6 1861 TCT 3 1655 N. Flaten NW8-8-16-2 84 TCS 4 1072 TCU 3 1024 TCT 8 832 * Fertilized )( PLOT sEer SOILS 0\ co - 69 -The BKW and BKY series are weakly developed Solonetzic soils, with soil profiles that have many of the characteristics of Solonetzic soils such as strong subangular blocky structure, clay and organic matter coatings in their B horizons but lacking the amount of B horizon development and salinity characteristics of the more strongly developed Solonetzic soils. The TCS, TCT and TCU soils are strongly developed Solonetzic soils. RESULTS AND DISCUSSION Yields at the Flaten site were considerably less than at the sites of the Torquay-Outram area (Table 1). The smaller amount of growing season rainfall at that site was partially responsible for the differ-ences, although the more strongly Solonetzic characteristics of the soil and general occurrence of saline soil ;at lesser depths were probably contributing factors also. Yields were generally lowest for the Solodized-Solonetz (TCT) series, with increase in yields in the sequence TCS (Solonetz), TCU (Solod) to highest and approximately equal yields for the weakly developed Solonetzic or intergrade series (BKW, BKY) and Orthic Dark Brown (AMA) series. A significant negative correlation (r = -0.41, R2 x 100 = 16.1) between yield and N03-N to. 60 em depth at seeding was surprising, and is probably related to other.factors ·such as the tough, impermeable B horizons and higher salinity characteristic of the series (TCT, TCS) with the largest amounts of N03-N. Some evidence for this is the significant negative correlation (r = -0.53, R2 x 100 = 28) betwe.en yield and soluble sodium percentage (SSP) of the B horizons. SSP has been used as a criterion for differentiating Solonetzic and Chernozemic soils, increasing with degree of Solonetzic B horizon development and with salinity level. The mean SSP values observed for the B~ and BKY indicate that desig-nating these soils as Solonetzic-Chernozemic intergrades was appropriate, although the range of values observed suggests that no single criterion will adequately separate these two groups from the typical Chernozemic and Solonetzic soils. At the Memory site, depth of extraction of moisture (Figure 2) was greatest for the TCU or Solod soils, a probable consequence of the relatively friable, permeable nature of the soil profile. Where tougher, impermeable B horizons occur as in the TCS and TCT (Solodized-Solonetz) the plant roots were able to extract significant amounts of moisture only from the mean surface depths, with little change in moisture content of the depths greater than 45 em. Similarly, the depths of moisture extraction was greatest for the Chernozemic AMA soil and reduced in the more strongly structured BKY and BKW soils (data not shown) . . SUMMARY A preliminary assessment of th~ data gathered in this study has revealed differences in yield among the different soil series. Best yields were observed for normal Chernozemic soils and almost equivalent yields for the Chernozemic-Solonetzic intergrade soils. Lower yields were characteristic of the true Solonetzic soils, particularly the Solodized-Solonetz series. Unusual relationships between available N supply and yield demonstrated that soil property-yield relationships are different for Solonetzic soils, pointing to the need for study of this 26 22 18 14 10 8 26 22 w 18 0:: ::> t- 14 (/) -0 ~ 10 ~ 8 ·0 26 22 18 14 10 -------- ...... TCT =-= ._.._. ....... -.---- ---- ....... ---=..-. - • . ----- - ....... --·· ...- ··- •• • "" •• ::..::..""=="' .. ~ - - - ----· ""~ ...... :;: .. .:::::::-- -......_ -- .. ...._ .. . ._ - .. .;::::..--- . ------. - ............. -----------........ ...._ ·-. -.-./ - ·· -- 60-75cm -----------TCS -- - ,.. - - - - 45-60 em =-=:..:.-:-::.-.- . -.- ....... ....... . - ... --= -::--- -:.- ..:..=::.:!..::..: ~;=t,;-,~ • :---__ ··~ • - - -.-~ • :::::::- .___ ---. .Jif' ' ........ .._ - ___,~ .... ..... .. ~ ' ' --·-·· ~· . ........... -··~ ··-_.. .. ....... ---.... - 7_ •. -- ----~ '="' .... ::-- .... ---- . ~~-..:......- / --- - 30·45cm -·- ·15-30cm 0-15cm - _,.·"""""· --:=-~·-...._.,. .......... . ~ '--------r::: ....... ~ ...... ...... ....... ..,. . _________ _ ....... __ ?' '/ FIG.2 CHANGES IN SOIL MOISTURE OVER THE GROWING SEASON AT THE MEMORY SITE -.I 0 Table 2. S.E. Productivity Study - 1975. kg/ha kg/ha (SSP) C Hor. Cond. Series 1f of kg/ha Mean Mean Water sol. mmhos/cm2 Replicates Mean Yield NO -N -60 3 em Avail P -15 em Na % in B at 250C AMA 7 2372±202 86.2±12.2 16.0±1.2 23.6 2.1 BKY 6 2317±145 104.9±19.7 21. 8±5. 3 33.4 2.9 -...! BKW 11 2272±145 100.1±7.6 18.2±1.3 33.7 2.4 I-' TCU 17 1981±149 110. 8±5. 7 21. 2±2. 2 39.1 3.6 TCS 19 1750±159 111.1±9. 7 19 .6±1. 8 58.9 5.9 TCT 15 1297±156 128.4±10.8 18.5±3.2 75.7 8.2 - 72 -soil group. Different soil series had differences in depth of moisture extraction, a phenomenon probably related to the physical properties of the B horizons. This project is continuing. 

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Productivity studies in the Weyburn map area

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