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Impact of Soil properties and Climate change on Nutrient Use Efficiency in Farmer’s Fields

RK Kaleeswari, P Devasenapathy, N Chellaiah and B Udhayakumar

Department of Agronomy, Tamil Nadu Agricultural University, Coimbatore, India
E mail sdharika@yahoo.co.in

Abstract

Experiments were conducted in farmer’s fields in southern India to measure grain yield per unit of fertiliser nitrogen (N), phosphorus (P) and potassium (K) applied. The aims of this experiment were: to compare the yield advantages of application of N, P and K together to N applied alone, and to elucidate the economics of fertilizer application for a rice–rice rotation grown in regions varying in climate and soil properties. Application of fertilizer N, P and K together resulted in significantly higher yield and net returns compared to the unfertilized control and other combinations of fertilizer N, P and K.

Keywords

Fertiliser, Nutrient, Farmer, Climate, Soil properties, Grain yield

Introduction

One of the major constraints to fertilizer use efficiency in Asia is an imbalance of applied nutrients. Nitrogen (N) applications tend to be too high in relation to the amount of potassium (K) and phosphate (PO4) used. In China and India, for every 10 units of N applied, 3 to 4 units of PO4 and 1 to 2 units of K are applied (Islam,1995). The world’s annual consumption of total fertilizers, N fertilizers, PO4 fertilizers, and K fertilizers is 34.6, 24.4, 6.6, and 3.7 kg/capita, respectively (Zhang and Zhang, 2007).This is partly the result of a difference in cost of different nutrients, and partly due to the lack of knowledge among farmers about the need for balanced fertilizer applications (Portch,1997). The objectives of this study were to measure grain yield per unit of fertilizer N, P and K applied, to compare yield advantages of balanced application of N P K over N alone and to elucidate the economics of fertilizer application in the rice–rice system on farmers’ fields located in regions varying in climate and soil properties.

Methods

The study was conducted in farmers’ fields in two districts of southern India. The Vilupuram district has a semi-arid sub-tropical climate and receives a mean annual rainfall of 420mm (North eastern agro-climatic zone) and the Kanyakumari district has a sub-humid climate with a mean annual rainfall of 1150mm (Southern agro-climatic zone). Experiments were conducted during 2005 and 2006 in the fields of 96 farmers with 48 fields in each district, in both the dry and wet seasons. The soils in the experimental sites in the Vilupuram district were categorised as low in N (118-225 kg/ha), P (6.3-10.2 kg/ha) and high in K (645-927 kg/ha) status; while soils in experimental sites of the Kanyakumari district had medium N (297-315 kg/ha), high P (25-43 kg /ha) and low K status (75-112 kg/ha).

Five 100 m2 plots were established in each field and each plot was randomly assigned one fertilizer treatment. The fertilizer N–P–K treatments were: control (0–0–0), N (N–0–0), NP (N–P–0), NK (N–0–K) and NPK (N–P–K), all at recommended rates (120:60:60 kg N-P-K/ ha). The application rates were recommended by the Department of Agriculture, Tamil Nadu based on soil test results. Nutrient-use efficiencies were measured in terms of partial factor productivity (PFP) (ratio of grain yield to the amount of nutrients applied) and agronomic efficiency (AE) of each nutrient (yield in fertilized plot-yield in control plot/amount of nutrient applied) (Cassman et al.,1996) The AE is an incremental efficiency from applied fertilizer N, P and K over the control. Economic evaluation of fertilizer N, P and K was made through marginal analysis using the cost of the produce and fertilizers.

Results

Yield was correlated with major nutrients applied. Application of fertilizer NPK resulted in significantly higher yield (3247 kg/ ha -5439 kg/ha) and net returns compared to the unfertilized and other combinations of fertilizer N, P and K (Table 1.). In the wet season, AE for N was higher than the unfertilized control plot in both the high rainfall zone and low rainfall zone. In both the wet and dry seasons, the PFP of fertilizer N, P and K applied together were higher than N, NP and NK fertilized plots in the high rainfall zone.

Table 1. Mean yield and nutrient use efficiency in agro-climatic zones

Treatments

Agro-climatic zones

North Eastern Zone

Southern zone

Grain yield (kg/ha)

AE

PFP

Grain yield (kg/ha)

AE

PFP

N0P0K0

2417

-

-

4690

    

NP0K0

2532

0.96

21.10

4765

0.63

39.70

NP0K

2915

2.02

15.44

4920

1.28

27.33

NPK

3247

2.77

16.19

5052

2.01

28.07

Control

874

3.46

13.53

5439

3.12

22.66

*AE- agronomic efficiency, PFP- partial factor productivity

Multiple regression equations were computed to study the impact of variation in soil (organic carbon, native soil NPK status) and climatic factors (solar radiation, rainfall and temperature) on PFP and AE of fertilizer N, P and K (Table 2.). High AE value of P in the NE zone were due to the low P status in native soil while a high AE value for K in the southern zone was due to low native soil K status (Table 1.).

Table2. Correlation coefficients (r) and regression constants (a, b) showing linear relationship (Y=a+bX) between yield in controls plots (Y0) and soil organic carbon and available N, P and K contents (X)

Season

R

a

b

t-stat

R2

P value
(<0.05)

Wet season

            

Soil Organic Carbon

0.35

1265

3076.8

3.05

0.113

0.0032

Available N

0.53

-1922

32.56

5.39

0.285

<0.0001

Available P

0.65

1579

53.38

7.57

0.440

<0.0001

Available K

0.55

783

8.41

5.56

0.298

<0.0001

Dry season

            

Soil Organic Carbon

0.42

658

3056.6

3.97

0.178

0.0002

Available N

0.49

-1328

23.98

4.88

0.246

<0.0001

Available P

0.53

1313

36.2

5.92

0.310

<0.0001

Available K

0.50

651

6.05

4.90

0.255

<0.0001

Figure 1. Partial factor productivity (PFP) and agronomic efficiency (AE) of applied nutrients in farmer’s fields. NE- North-Eastern district, WS-wet season, DS- dry season.

Conclusions

This study on nutrient use efficiency showed that the yield of a rice-rice cropping system could be increased by balancing N, P and K application rates. Irrespective of the variation in the climatic conditions the crop responses to balanced macronutrient applications were high. In soil with low nutrient status there was better crop response to fertilisation. The balanced fertilisation of macronutrients by farmers would reduce the environmental pollution and increase nutrient use efficiency which would be more cost effective for farmers.

References

Cassman GC, Gines MA, Dizon MI, Samson and Alcantara JM (1996). Nitrogen use efficiency in tropical lowland rice systems: contribution from indigenous and applied nitrogen. Field Crops Research 47, 1–12.

Islam N., ed. 1995. “Population and Food in the Early 21st Century: Meeting Future Food Demand of an Increasing World Population.” Occasional Paper, International Food Policy Research Institute (IFPRI), Washington, DC, pp. 202.

Portch S (1997) Problems and Future Needs for Balanced Fertilization in China: A Summary. Better Crops International 11, 30-35

Zhang W and Zhang X (2007) A forecast analysis on fertilizer consumption worldwide. Environmental monitoring and Assessment 133, 427-434.

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