Table 1. The Effect of integrated application of NP/NPK fertilizers and FYM on the grain

yield of wheat at acidic soils of Chencha and HagreSelam areas of Southern Ethiopia

THE ROLE OF SOIL ACIDITY AND SOIL FERTILITY MANAGEMENT FOR ENHANCED AND

SUSTAINED PRODUTION OF WHEAT IN SOUTHERN ETHIOPIA

Wassie Haile

Abstract

Wheat production in south Ethiopia is constrained by declining soil fertility and soil acidity. To address these constraints, experiments on effect of integrated application of organic-inorganic fertilizers and lime application, effect of transferred biomass of Erythrina bruci and of-farm K verification trail were conducted on acidic soils of Chencha and Hagreselam in the last five years. The results revealed that application of N and P at 23:20:0 and 46:40:0 kg/ha in the form of urea and TSP did not significantly increase the yield of wheat compared with the control at Chencha. But combined application of NP with 5 and 10 t/ha of farmyard manure (FYM) significantly increased the grain yield. NP applied at 46:40kg/ha + 10 tha FYM increased the grain yield by 454% and 297% over the control and NP treatment applied at 46:40:0 kg/ha alone respectively att Chencha. Application of NP with potassium (K) have also significantly increased the grain yield wheat compared with NP, control and FYM treatments. Similarly, integrated application NP + FYM and NP + K treatments significantly increased the grain yield of wheat at Hagreselam in 2007, compared with control and either source applied alone. This implies that K is a limiting nutrient in both Chencha and Hagereselam areas. On-farm verification study results proved that K is a limiting nutrient for wheat production in acidic soils of south. Application of lime with NP fertilizers significantly increased the yield of wheat in these areas but the magnitude of yield improvement was not so high relative to that obtained with integrated application of inorganic-organic fertilizers and NPK treatments. E. bruci biomass applied 10 t/ha increased the grain yield by 127% over the control and produced the same yield as that obtained with recommended dose of NP (46:40 kg/ha) fertilizer at Kokate location. If NP fertilizers are continued to be applied, It must be applied along with either with organic fertilizer such as FYM or K. The importance of K as a limiting nutrient at Chencha and Hagereselam areas has now been proved against the longstanding conclusion that Ethiopian soils were rich in K. Thus, importation of K fertilizers might be necessary. E. bruci as an organic fertilizer should be promoted in areas where it exists abundantly.

Key word: Inorganic fertilizers, Organic fertilizer, integrated soil fertility management, wheat, Ethiopia

College of Agriculture, Hawasa University, P.O.Box 05, Hawasa, Ethiopia. Email wassiehaile@yahoo.co.uk

No

Treatments

Grain Yield (q/ha)

Chencha Hagreselam

1 N0P0 + 0 FYM 6.1h 13.5d

2 N0P0 + 5 FYM 13.0gh 23.7bc

3 N0P0 + 10 FYM 17.8g 26.8abc

4 N23P20 + 0 FYM 11.3gh 26.8abcd

5 N23P20 + 5 FYM 22.1cde 27.6acd

6 N23P20 + 10 FYM 23.7bcde 29.4abc

7 N46P40 + 0 FYM 11.0gh 20cd

8 N46P40 +5 FYM 21.3def 34.6a

9 N46P40 + 10 FYM 31.0ab 29.4abc

10 N23P20K25 + 0 FYM 22.8bcde 27.6abcd

11 N23P20K25 + 5 FYM 28.0abcd 29.4abc

12 N23P20K25 + 10 FYM 33.3a 34.4a

13 N46P40K50 + 0 FYM 23.8bcd 32.8a

14 N46P40K50 + 5 FYM 30.7abc 34.1a

15 N46P40K50 +1 0 FYM 35.7a 34.9a

LSD 8.7 9.5

CV 22 19

Table 2. The effect of potassium and sulphur applied singly or in combination on the yield of wheat

grown on different soil types in SNNPR in 2011.

INTRODUCTION

Declining soil fertility and soil acidity is one of the major challenges to wheat production in the southern Ethiopia.

Application of inorganic fertilizer can adress the problem. But its cost is increasingly. more repeated use of ferilizers aggravate the depeletion of other macro and micro nutrients nutrients, acidify

soil,, promotes depletion of OM etc.. Recently K is found to be limiting in some soils of Ethiooipia ( Abiye et al., 2004; Wassie, 2009). There are also soils which do not respond to NP application in the south. Thus, there is a need for the development and use of sound integrated soil fertility and acidity management

technology to improve and sustain crop production in Ethiopia.

To these effects the effect of combined application of NP/NPK fertilizers with farm yard manue (FYM )and effect of lime on wheat have been studied at acidic soils of Chencha and Hagreselam areas, south Ethiopia.

The role of Erythrina bruci, nutrient rich, N-fixing endemic tree to Ethiopia in increasing the yield of wheat have

also been investigated

The experiment was conducted at Chencha & HagereSelam located at 37º.60’ E and 6º.13’ N . 6014‘ N & 38042‘ E

respectivelly.The soils of both areas are strongly acidic and P and K limited. A factorial experiment consisting 3 levels (0, 5 and 10 tha-1) of farm yard manure (FYM) and 5 levels of NPK fertilizers (0:0:0,

23:20:0, 46:40:0, 23:20:25 and 46:40:50 kgha-1) , laid out in RCB design with three replications. Wheat variety Simba was planted as a test crop..

NP treatments did not affect the grain yield at Chencha significantly increased the yield when combined with 5 and 10 t/ha

FYM (Table 1). The highest grain yield was obtained from N46P40K50 + 10 t/ha FYM, N23P20K25 + 10 FYM and N46P40 + 10 t/ha FYM in that order

at Chencha. This implies that FYM has served as K source inaddition to other nutrients and none nutritional benefits.

I. Effect of integrated application of NP/NPK fertlizers and farm yard manure (FYM) on the grain yield of wheat at acidic soils of Chencha and Hagreselam, South Ethiopia

II. The effect of lime and NPK fertilizers on the yield of wheat

The effect of lime (0, 1.75 t/ha and 3.5 t/ha) was studied in a factorial combination of NP, NK PK and NPK fertilizers on wheat at adic soils Hgreselam and chencha, southern Ethiopia in 2007-09.

Figure 1. Effect of lime and NPK fertilizers on the grain yield of wheat at HagreSelam in 2007

*N0P0 = 0:0 kg/ha N & P, N23P20 = 23:20 kg/ha N & P, N46P40 : 46:40 kg/ha N& P, N23P20K0 = 23:20:25

kg/ha N, P & K and N46P40K50 = 46:40:50 kg/ha N & P

The results revealed lime at full dose has only slightly improved the grain yield (Fig. 1). But with NP and NK has and significantly increased compared with control and lime treatments. However, with NPK, application of lime did not produce significant yield difference compared with NPK treatmen alone. PK treatmnent produced significantly higher yield than that NP and NK indicating that the soil is P & K limited than N.

III. The effect of K and sulpher applied singly or in combination on the yield of wheat at on farmers, field HagreSelam conducted in 2011

The effect of K and sulphur on the yield of wheat was studied at Hagreselam area in 2011 on farmers’ field. The grain and biomass yields of wheat were found to be significantly affected by different treatments. The highest grain yield of wheat was obtained from 50 kg/ha urea + 100 kg/ha DAP +43.33 KCl+50 CaSO4 than all other treatments (Table 2). The next highest yield was obtained from 50 urea + 100 DAP+ 50 kg/ha CaSO4 .

IV.Effect of Erythrina bruci green biomass on th grain yield of wheat at Kokate, SNNPR

The effce of green biomass of Erythrina bruci which is N-fixing and nutrient rich tree on the yield of wheat

have been studied at Kokate, south Ethiopia for two years (2010-2011). Sole application of E. bruci biomass at 10 t/ha increased the grain yield by 127% over the control and produced the same yield as that produced by recommended fertilizer for wheat production in Kokate area (Fig. 2). The highest yield however was obtained from 50:50 combined application of inorganic and E.bruci biomass.

Fig. 2. The effect of E. Bruci green biomass on the grain yield of wheat at Kokate over two years (2010-2011)

** a =control, b= 92 kg/ha N, c= 69 kg N/ha + 2.5 t/ha E. Bruci fresh biomass, d = 46 kg/ha N + 5 t/ha E. Bruci fresh biomass, e = 23 kg/ha N + 7.5 t/ha E. Bruci fresh biomass and f = 10 t/ha E bruci fresh biomass

Conclusions Application of NP fertilizer did not significantly increase the yield of wheat at chencha location

But when it is applied with K or fram yard manure, the yield was significntly increased mplying that K is a limiting factor in the study areas.

At Hagreselam area, NP has ignificantly increased the grain yield of wheat but it was further increased with FYM or K

Application of limealone has only slightly increased yield of wheat in both locations But the grain yield was significantly and appreciably increased when lime was applied with NP

With NPK, lime did not change the yield produced

Onfarm verfification resultat hagreselam indicate that K is am limiting nutient at farmers field sugesting that K fertilizer should be applied

Erythina bruci green biomass produced significantly higher yield of wheat at Kokate, Wolaita Soddo comapred with control and produced same yield of wheat as that yield that can be obtained with 46/40 kg/ha NP fertilizers

Recommendations

If only inorganic fertilizers are to be applied, balanced applications of NPK at 23:20:25 kgha-

1 and 46:40:50 kgha-1 for Chencha and hagreSelam location is recommended for wheat production respectivelly.

Highigher yield If integrated application is to be the option 23:20:25 kg/ha NPK + 10 t/ha FYM is

Manure has to be applied at 10 t/ha or for best results Potassium is found to be limiting nutrient to wheat thus is recomded that , K fertilizer applied

at Chencha and Selam areas. Application of lime as a means to mitigate soil acidity in the sudy ares have limited benfit

thus other options for combting soil acidity should be sought Application of fresh biomass of E bruci at 10 t/ha is recommended for wheat production in

Kokate area